+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+N\bNA\bAM\bME\bE
+ csh - a shell (command interpreter) with C-like syntax
+
+S\bSY\bYN\bNO\bOP\bPS\bSI\bIS\bS
+ c\bcs\bsh\bh [ -\b-c\bce\bef\bfi\bin\bns\bst\btv\bvV\bVx\bxX\bX ] [ arg ... ]
+
+D\bDE\bES\bSC\bCR\bRI\bIP\bPT\bTI\bIO\bON\bN
+ _\bC_\bs_\bh is a first implementation of a command language inter-
+ preter incorporating a history mechanism (see H\bHi\bis\bst\bto\bor\bry\by S\bSu\bub\bb-\b-
+ s\bst\bti\bit\btu\but\bti\bio\bon\bns\bs), job control facilities (see J\bJo\bob\bbs\bs), interactive
+ file name and user name completion (see F\bFi\bil\ble\be N\bNa\bam\bme\be C\bCo\bom\bmp\bpl\ble\be-\b-
+ t\bti\bio\bon\bn), and a C-like syntax. So as to be able to use its job
+ control facilities, users of _\bc_\bs_\bh must (and automatically)
+ use the new tty driver fully described in _\bt_\bt_\by(4). This new
+ tty driver allows generation of interrupt characters from
+ the keyboard to tell jobs to stop. See _\bs_\bt_\bt_\by(1) for details
+ on setting options in the new tty driver.
+
+ An instance of _\bc_\bs_\bh begins by executing commands from the
+ file `.cshrc' in the _\bh_\bo_\bm_\be directory of the invoker. If this
+ is a login shell then it also executes commands from the
+ file `.login' there. It is typical for users on crt's to
+ put the command ``stty crt'' in their ._\bl_\bo_\bg_\bi_\bn file, and to
+ also invoke _\bt_\bs_\be_\bt(1) there.
+
+ In the normal case, the shell will then begin reading com-
+ mands from the terminal, prompting with `% '. Processing of
+ arguments and the use of the shell to process files contain-
+ ing command scripts will be described later.
+
+ The shell then repeatedly performs the following actions: a
+ line of command input is read and broken into _\bw_\bo_\br_\bd_\bs. This
+ sequence of words is placed on the command history list and
+ then parsed. Finally each command in the current line is
+ executed.
+
+ When a login shell terminates it executes commands from the
+ file `.logout' in the users home directory.
+
+ L\bLe\bex\bxi\bic\bca\bal\bl s\bst\btr\bru\buc\bct\btu\bur\bre\be
+
+ The shell splits input lines into words at blanks and tabs
+ with the following exceptions. The characters `&' `|' `;'
+ `<' `>' `(' `)' form separate words. If doubled in `&&',
+ `||', `<<' or `>>' these pairs form single words. These
+ parser metacharacters may be made part of other words, or
+ prevented their special meaning, by preceding them with `\'.
+ A newline preceded by a `\' is equivalent to a blank.
+
+ In addition strings enclosed in matched pairs of quotations,
+ `'', ``' or `"', form parts of a word; metacharacters in
+ these strings, including blanks and tabs, do not form
+
+
+
+Printed 7/9/88 April 24, 1988 1
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ separate words. These quotations have semantics to be
+ described subsequently. Within pairs of `'' or `"' charac-
+ ters a newline preceded by a `\' gives a true newline char-
+ acter.
+
+ When the shell's input is not a terminal, the character `#'
+ introduces a comment which continues to the end of the input
+ line. It is prevented this special meaning when preceded by
+ `\' and in quotations using ``', `'', and `"'.
+
+ C\bCo\bom\bmm\bma\ban\bnd\bds\bs
+
+ A simple command is a sequence of words, the first of which
+ specifies the command to be executed. A simple command or a
+ sequence of simple commands separated by `|' characters
+ forms a pipeline. The output of each command in a pipeline
+ is connected to the input of the next. Sequences of pipe-
+ lines may be separated by `;', and are then executed sequen-
+ tially. A sequence of pipelines may be executed without
+ immediately waiting for it to terminate by following it with
+ an `&'.
+
+ Any of the above may be placed in `(' `)' to form a simple
+ command (which may be a component of a pipeline, etc.) It is
+ also possible to separate pipelines with `||' or `&&' indi-
+ cating, as in the C language, that the second is to be exe-
+ cuted only if the first fails or succeeds respectively. (See
+ _\bE_\bx_\bp_\br_\be_\bs_\bs_\bi_\bo_\bn_\bs.)
+
+ J\bJo\bob\bbs\bs
+
+ The shell associates a _\bj_\bo_\bb with each pipeline. It keeps a
+ table of current jobs, printed by the _\bj_\bo_\bb_\bs command, and
+ assigns them small integer numbers. When a job is started
+ asynchronously with `&', the shell prints a line which looks
+ like:
+
+ [1] 1234
+
+ indicating that the job which was started asynchronously was
+ job number 1 and had one (top-level) process, whose process
+ id was 1234.
+
+ If you are running a job and wish to do something else you
+ may hit the key ^\b^Z\bZ (control-Z) which sends a STOP signal to
+ the current job. The shell will then normally indicate that
+ the job has been `Stopped', and print another prompt. You
+ can then manipulate the state of this job, putting it in the
+ background with the _\bb_\bg command, or run some other commands
+ and then eventually bring the job back into the foreground
+ with the foreground command _\bf_\bg. A ^\b^Z\bZ takes effect immedi-
+ ately and is like an interrupt in that pending output and
+
+
+
+Printed 7/9/88 April 24, 1988 2
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ unread input are discarded when it is typed. There is
+ another special key ^\b^Y\bY which does not generate a STOP signal
+ until a program attempts to _\br_\be_\ba_\bd(2) it. This can usefully
+ be typed ahead when you have prepared some commands for a
+ job which you wish to stop after it has read them.
+
+ A job being run in the background will stop if it tries to
+ read from the terminal. Background jobs are normally
+ allowed to produce output, but this can be disabled by giv-
+ ing the command ``stty tostop''. If you set this tty
+ option, then background jobs will stop when they try to pro-
+ duce output like they do when they try to read input.
+
+ There are several ways to refer to jobs in the shell. The
+ character `%' introduces a job name. If you wish to refer
+ to job number 1, you can name it as `%1'. Just naming a job
+ brings it to the foreground; thus `%1' is a synonym for `fg
+ %1', bringing job 1 back into the foreground. Similarly
+ saying `%1 &' resumes job 1 in the background. Jobs can
+ also be named by prefixes of the string typed in to start
+ them, if these prefixes are unambiguous, thus `%ex' would
+ normally restart a suspended _\be_\bx(1) job, if there were only
+ one suspended job whose name began with the string `ex'. It
+ is also possible to say `%?string' which specifies a job
+ whose text contains _\bs_\bt_\br_\bi_\bn_\bg, if there is only one such job.
+
+ The shell maintains a notion of the current and previous
+ jobs. In output pertaining to jobs, the current job is
+ marked with a `+' and the previous job with a `-'. The
+ abbreviation `%+' refers to the current job and `%-' refers
+ to the previous job. For close analogy with the syntax of
+ the _\bh_\bi_\bs_\bt_\bo_\br_\by mechanism (described below), `%%' is also a
+ synonym for the current job.
+
+ S\bSt\bta\bat\btu\bus\bs r\bre\bep\bpo\bor\brt\bti\bin\bng\bg
+
+ This shell learns immediately whenever a process changes
+ state. It normally informs you whenever a job becomes
+ blocked so that no further progress is possible, but only
+ just before it prints a prompt. This is done so that it
+ does not otherwise disturb your work. If, however, you set
+ the shell variable _\bn_\bo_\bt_\bi_\bf_\by, the shell will notify you immedi-
+ ately of changes of status in background jobs. There is
+ also a shell command _\bn_\bo_\bt_\bi_\bf_\by which marks a single process so
+ that its status changes will be immediately reported. By
+ default _\bn_\bo_\bt_\bi_\bf_\by marks the current process; simply say
+ `notify' after starting a background job to mark it.
+
+ When you try to leave the shell while jobs are stopped, you
+ will be warned that `You have stopped jobs.' You may use
+ the _\bj_\bo_\bb_\bs command to see what they are. If you do this or
+ immediately try to exit again, the shell will not warn you a
+
+
+
+Printed 7/9/88 April 24, 1988 3
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ second time, and the suspended jobs will be terminated.
+
+ F\bFi\bil\ble\be N\bNa\bam\bme\be C\bCo\bom\bmp\bpl\ble\bet\bti\bio\bon\bn
+
+ When the file name completion feature is enabled by setting
+ the shell variable _\bf_\bi_\bl_\be_\bc (see s\bse\bet\bt), _\bc_\bs_\bh will interactively
+ complete file names and user names from unique prefixes,
+ when they are input from the terminal followed by the escape
+ character (the escape key, or control-[). For example, if
+ the current directory looks like
+ DSC.OLD bin cmd lib xmpl.c
+ DSC.NEW chaosnet cmtest mail xmpl.o
+ bench class dev mbox xmpl.out
+ and the input is
+ % vi ch<escape>
+ _\bc_\bs_\bh will complete the prefix ``ch'' to the only matching
+ file name ``chaosnet'', changing the input line to
+ % vi chaosnet
+ However, given
+ % vi D<escape>
+ _\bc_\bs_\bh will only expand the input to
+ % vi DSC.
+ and will sound the terminal bell to indicate that the expan-
+ sion is incomplete, since there are two file names matching
+ the prefix ``D''.
+
+ If a partial file name is followed by the end-of-file char-
+ acter (usually control-D), then, instead of completing the
+ name, _\bc_\bs_\bh will list all file names matching the prefix. For
+ example, the input
+ % vi D<control-D>
+ causes all files beginning with ``D'' to be listed:
+ DSC.NEW DSC.OLD
+ while the input line remains unchanged.
+
+ The same system of escape and end-of-file can also be used
+ to expand partial user names, if the word to be completed
+ (or listed) begins with the character ``~''. For example,
+ typing
+ cd ~ro<escape>
+ may produce the expansion
+ cd ~root
+
+ The use of the terminal bell to signal errors or multiple
+ matches can be inhibited by setting the variable _\bn_\bo_\bb_\be_\be_\bp.
+
+ Normally, all files in the particular directory are candi-
+ dates for name completion. Files with certain suffixes can
+ be excluded from consideration by setting the variable _\bf_\bi_\bg_\b-
+ _\bn_\bo_\br_\be to the list of suffixes to be ignored. Thus, if _\bf_\bi_\bg_\b-
+ _\bn_\bo_\br_\be is set by the command
+ % set fignore = (.o .out)
+
+
+
+Printed 7/9/88 April 24, 1988 4
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ then typing
+ % vi x<escape>
+ would result in the completion to
+ % vi xmpl.c
+ ignoring the files "xmpl.o" and "xmpl.out". However, if the
+ only completion possible requires not ignoring these suf-
+ fixes, then they are not ignored. In addition, _\bf_\bi_\bg_\bn_\bo_\br_\be does
+ not affect the listing of file names by control-D. All
+ files are listed regardless of their suffixes.
+
+ S\bSu\bub\bbs\bst\bti\bit\btu\but\bti\bio\bon\bns\bs
+
+ We now describe the various transformations the shell per-
+ forms on the input in the order in which they occur.
+
+ H\bHi\bis\bst\bto\bor\bry\by s\bsu\bub\bbs\bst\bti\bit\btu\but\bti\bio\bon\bns\bs
+
+ History substitutions place words from previous command
+ input as portions of new commands, making it easy to repeat
+ commands, repeat arguments of a previous command in the
+ current command, or fix spelling mistakes in the previous
+ command with little typing and a high degree of confidence.
+ History substitutions begin with the character `!' and may
+ begin a\ban\bny\byw\bwh\bhe\ber\bre\be in the input stream (with the proviso that
+ they d\bdo\bo n\bno\bot\bt nest.) This `!' may be preceded by an `\' to
+ prevent its special meaning; for convenience, a `!' is
+ passed unchanged when it is followed by a blank, tab, new-
+ line, `=' or `('. (History substitutions also occur when an
+ input line begins with `^'. This special abbreviation will
+ be described later.) Any input line which contains history
+ substitution is echoed on the terminal before it is executed
+ as it could have been typed without history substitution.
+
+ Commands input from the terminal which consist of one or
+ more words are saved on the history list. The history sub-
+ stitutions reintroduce sequences of words from these saved
+ commands into the input stream. The size of which is con-
+ trolled by the _\bh_\bi_\bs_\bt_\bo_\br_\by variable; the previous command is
+ always retained, regardless of its value. Commands are num-
+ bered sequentially from 1.
+
+ For definiteness, consider the following output from the
+ _\bh_\bi_\bs_\bt_\bo_\br_\by command:
+
+ 9 write michael
+ 10 ex write.c
+ 11 cat oldwrite.c
+ 12 diff *write.c
+
+ The commands are shown with their event numbers. It is not
+ usually necessary to use event numbers, but the current
+ event number can be made part of the _\bp_\br_\bo_\bm_\bp_\bt by placing an
+
+
+
+Printed 7/9/88 April 24, 1988 5
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ `!' in the prompt string.
+
+ With the current event 13 we can refer to previous events by
+ event number `!11', relatively as in `!-2' (referring to the
+ same event), by a prefix of a command word as in `!d' for
+ event 12 or `!wri' for event 9, or by a string contained in
+ a word in the command as in `!?mic?' also referring to event
+ 9. These forms, without further modification, simply rein-
+ troduce the words of the specified events, each separated by
+ a single blank. As a special case `!!' refers to the previ-
+ ous command; thus `!!' alone is essentially a _\br_\be_\bd_\bo.
+
+ To select words from an event we can follow the event
+ specification by a `:' and a designator for the desired
+ words. The words of an input line are numbered from 0, the
+ first (usually command) word being 0, the second word (first
+ argument) being 1, etc. The basic word designators are:
+
+ 0 first (command) word
+ _\bn _\bn'th argument
+ ^ first argument, i.e. `1'
+ $ last argument
+ % word matched by (immediately preceding) ?_\bs? search
+ _\bx-_\by range of words
+ -_\by abbreviates `0-_\by'
+ * abbreviates `^-$', or nothing if only 1 word in event
+ _\bx* abbreviates `_\bx-$'
+ _\bx- like `_\bx*' but omitting word `$'
+
+ The `:' separating the event specification from the word
+ designator can be omitted if the argument selector begins
+ with a `^', `$', `*' `-' or `%'. After the optional word
+ designator can be placed a sequence of modifiers, each pre-
+ ceded by a `:'. The following modifiers are defined:
+
+ h Remove a trailing pathname component, leaving the head.
+ r Remove a trailing `.xxx' component, leaving the root name.
+ e Remove all but the extension `.xxx' part.
+ s/_\bl/_\br/ Substitute _\bl for _\br
+ t Remove all leading pathname components, leaving the tail.
+ & Repeat the previous substitution.
+ g Apply the change globally, prefixing the above, e.g. `g&'.
+ p Print the new command line but do not execute it.
+ q Quote the substituted words, preventing further substitutions.
+ x Like q, but break into words at blanks, tabs and newlines.
+
+ Unless preceded by a `g' the modification is applied only to
+ the first modifiable word. With substitutions, it is an
+ error for no word to be applicable.
+
+ The left hand side of substitutions are not regular expres-
+ sions in the sense of the editors, but rather strings. Any
+
+
+
+Printed 7/9/88 April 24, 1988 6
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ character may be used as the delimiter in place of `/'; a
+ `\' quotes the delimiter into the _\bl and _\br strings. The
+ character `&' in the right hand side is replaced by the text
+ from the left. A `\' quotes `&' also. A null _\bl uses the
+ previous string either from a _\bl or from a contextual scan
+ string _\bs in `!?_\bs?'. The trailing delimiter in the substitu-
+ tion may be omitted if a newline follows immediately as may
+ the trailing `?' in a contextual scan.
+
+ A history reference may be given without an event specifica-
+ tion, e.g. `!$'. In this case the reference is to the pre-
+ vious command unless a previous history reference occurred
+ on the same line in which case this form repeats the previ-
+ ous reference. Thus `!?foo?^ !$' gives the first and last
+ arguments from the command matching `?foo?'.
+
+ A special abbreviation of a history reference occurs when
+ the first non-blank character of an input line is a `^'.
+ This is equivalent to `!:s^' providing a convenient short-
+ hand for substitutions on the text of the previous line.
+ Thus `^lb^lib' fixes the spelling of `lib' in the previous
+ command. Finally, a history substitution may be surrounded
+ with `{' and `}' if necessary to insulate it from the char-
+ acters which follow. Thus, after `ls -ld ~paul' we might do
+ `!{l}a' to do `ls -ld ~paula', while `!la' would look for a
+ command starting `la'.
+
+ Q\bQu\buo\bot\bta\bat\bti\bio\bon\bns\bs w\bwi\bit\bth\bh '\b' a\ban\bnd\bd "\b"
+
+ The quotation of strings by `'' and `"' can be used to
+ prevent all or some of the remaining substitutions. Strings
+ enclosed in `'' are prevented any further interpretation.
+ Strings enclosed in `"' may be expanded as described below.
+
+ In both cases the resulting text becomes (all or part of) a
+ single word; only in one special case (see _\bC_\bo_\bm_\bm_\ba_\bn_\bd _\bS_\bu_\bb_\bs_\bt_\bi_\bt_\bi_\b-
+ _\bt_\bi_\bo_\bn below) does a `"' quoted string yield parts of more
+ than one word; `'' quoted strings never do.
+
+ A\bAl\bli\bia\bas\bs s\bsu\bub\bbs\bst\bti\bit\btu\but\bti\bio\bon\bn
+
+ The shell maintains a list of aliases which can be esta-
+ blished, displayed and modified by the _\ba_\bl_\bi_\ba_\bs and _\bu_\bn_\ba_\bl_\bi_\ba_\bs
+ commands. After a command line is scanned, it is parsed
+ into distinct commands and the first word of each command,
+ left-to-right, is checked to see if it has an alias. If it
+ does, then the text which is the alias for that command is
+ reread with the history mechanism available as though that
+ command were the previous input line. The resulting words
+ replace the command and argument list. If no reference is
+ made to the history list, then the argument list is left
+ unchanged.
+
+
+
+Printed 7/9/88 April 24, 1988 7
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ Thus if the alias for `ls' is `ls -l' the command `ls /usr'
+ would map to `ls -l /usr', the argument list here being
+ undisturbed. Similarly if the alias for `lookup' was `grep
+ !^ /etc/passwd' then `lookup bill' would map to `grep bill
+ /etc/passwd'.
+
+ If an alias is found, the word transformation of the input
+ text is performed and the aliasing process begins again on
+ the reformed input line. Looping is prevented if the first
+ word of the new text is the same as the old by flagging it
+ to prevent further aliasing. Other loops are detected and
+ cause an error.
+
+ Note that the mechanism allows aliases to introduce parser
+ metasyntax. Thus we can `alias print 'pr \!* | lpr'' to
+ make a command which _\bp_\br'_\bs its arguments to the line printer.
+
+ V\bVa\bar\bri\bia\bab\bbl\ble\be s\bsu\bub\bbs\bst\bti\bit\btu\but\bti\bio\bon\bn
+
+ The shell maintains a set of variables, each of which has as
+ value a list of zero or more words. Some of these variables
+ are set by the shell or referred to by it. For instance,
+ the _\ba_\br_\bg_\bv variable is an image of the shell's argument list,
+ and words of this variable's value are referred to in spe-
+ cial ways.
+
+ The values of variables may be displayed and changed by
+ using the _\bs_\be_\bt and _\bu_\bn_\bs_\be_\bt commands. Of the variables referred
+ to by the shell a number are toggles; the shell does not
+ care what their value is, only whether they are set or not.
+ For instance, the _\bv_\be_\br_\bb_\bo_\bs_\be variable is a toggle which causes
+ command input to be echoed. The setting of this variable
+ results from the -\b-v\bv command line option.
+
+ Other operations treat variables numerically. The `@' com-
+ mand permits numeric calculations to be performed and the
+ result assigned to a variable. Variable values are, how-
+ ever, always represented as (zero or more) strings. For the
+ purposes of numeric operations, the null string is con-
+ sidered to be zero, and the second and subsequent words of
+ multiword values are ignored.
+
+ After the input line is aliased and parsed, and before each
+ command is executed, variable substitution is performed
+ keyed by `$' characters. This expansion can be prevented by
+ preceding the `$' with a `\' except within `"'s where it
+ a\bal\blw\bwa\bay\bys\bs occurs, and within `''s where it n\bne\bev\bve\ber\br occurs.
+ Strings quoted by ``' are interpreted later (see _\bC_\bo_\bm_\bm_\ba_\bn_\bd
+ _\bs_\bu_\bb_\bs_\bt_\bi_\bt_\bu_\bt_\bi_\bo_\bn below) so `$' substitution does not occur there
+ until later, if at all. A `$' is passed unchanged if fol-
+ lowed by a blank, tab, or end-of-line.
+
+
+
+
+Printed 7/9/88 April 24, 1988 8
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ Input/output redirections are recognized before variable
+ expansion, and are variable expanded separately. Otherwise,
+ the command name and entire argument list are expanded
+ together. It is thus possible for the first (command) word
+ to this point to generate more than one word, the first of
+ which becomes the command name, and the rest of which become
+ arguments.
+
+ Unless enclosed in `"' or given the `:q' modifier the
+ results of variable substitution may eventually be command
+ and filename substituted. Within `"', a variable whose
+ value consists of multiple words expands to a (portion of) a
+ single word, with the words of the variables value separated
+ by blanks. When the `:q' modifier is applied to a substitu-
+ tion the variable will expand to multiple words with each
+ word separated by a blank and quoted to prevent later com-
+ mand or filename substitution.
+
+ The following metasequences are provided for introducing
+ variable values into the shell input. Except as noted, it
+ is an error to reference a variable which is not set.
+
+ $name
+ ${name}
+ Are replaced by the words of the value of variable
+ _\bn_\ba_\bm_\be, each separated by a blank. Braces insulate _\bn_\ba_\bm_\be
+ from following characters which would otherwise be part
+ of it. Shell variables have names consisting of up to
+ 20 letters and digits starting with a letter. The
+ underscore character is considered a letter.
+ If _\bn_\ba_\bm_\be is not a shell variable, but is set in the
+ environment, then that value is returned (but :\b: modif-
+ iers and the other forms given below are not available
+ in this case).
+
+ $name[selector]
+ ${name[selector]}
+ May be used to select only some of the words from the
+ value of _\bn_\ba_\bm_\be. The selector is subjected to `$' substi-
+ tution and may consist of a single number or two
+ numbers separated by a `-'. The first word of a vari-
+ ables value is numbered `1'. If the first number of a
+ range is omitted it defaults to `1'. If the last
+ member of a range is omitted it defaults to `$#name'.
+ The selector `*' selects all words. It is not an error
+ for a range to be empty if the second argument is omit-
+ ted or in range.
+
+ $#name
+ ${#name}
+ Gives the number of words in the variable. This is
+ useful for later use in a `[selector]'.
+
+
+
+Printed 7/9/88 April 24, 1988 9
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ $0
+ Substitutes the name of the file from which command
+ input is being read. An error occurs if the name is
+ not known.
+
+ $number
+ ${number}
+ Equivalent to `$argv[number]'.
+
+ $*
+ Equivalent to `$argv[*]'.
+
+ The modifiers `:e', `:h', `:t', `:r', `:q' and `:x' may be
+ applied to the substitutions above as may `:gh', `:gt' and
+ `:gr'. If braces `{' '}' appear in the command form then
+ the modifiers must appear within the braces. T\bTh\bhe\be c\bcu\bur\brr\bre\ben\bnt\bt
+ i\bim\bmp\bpl\ble\bem\bme\ben\bnt\bta\bat\bti\bio\bon\bn a\bal\bll\blo\bow\bws\bs o\bon\bnl\bly\by o\bon\bne\be `\b`:\b:'\b' m\bmo\bod\bdi\bif\bfi\bie\ber\br o\bon\bn e\bea\bac\bch\bh `\b`$\b$'\b'
+ e\bex\bxp\bpa\ban\bns\bsi\bio\bon\bn.\b.
+
+ The following substitutions may not be modified with `:'
+ modifiers.
+
+ $?name
+ ${?name}
+ Substitutes the string `1' if name is set, `0' if it is
+ not.
+
+ $?0
+ Substitutes `1' if the current input filename is known,
+ `0' if it is not.
+
+ $$
+ Substitute the (decimal) process number of the (parent)
+ shell.
+
+ $<
+ Substitutes a line from the standard input, with no
+ further interpretation thereafter. It can be used to
+ read from the keyboard in a shell script.
+
+ C\bCo\bom\bmm\bma\ban\bnd\bd a\ban\bnd\bd f\bfi\bil\ble\ben\bna\bam\bme\be s\bsu\bub\bbs\bst\bti\bit\btu\but\bti\bio\bon\bn
+
+ The remaining substitutions, command and filename substitu-
+ tion, are applied selectively to the arguments of builtin
+ commands. This means that portions of expressions which are
+ not evaluated are not subjected to these expansions. For
+ commands which are not internal to the shell, the command
+ name is substituted separately from the argument list. This
+ occurs very late, after input-output redirection is per-
+ formed, and in a child of the main shell.
+
+
+
+
+
+Printed 7/9/88 April 24, 1988 10
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ C\bCo\bom\bmm\bma\ban\bnd\bd s\bsu\bub\bbs\bst\bti\bit\btu\but\bti\bio\bon\bn
+
+ Command substitution is indicated by a command enclosed in
+ ``'. The output from such a command is normally broken into
+ separate words at blanks, tabs and newlines, with null words
+ being discarded, this text then replacing the original
+ string. Within `"'s, only newlines force new words; blanks
+ and tabs are preserved.
+
+ In any case, the single final newline does not force a new
+ word. Note that it is thus possible for a command substitu-
+ tion to yield only part of a word, even if the command out-
+ puts a complete line.
+
+ F\bFi\bil\ble\ben\bna\bam\bme\be s\bsu\bub\bbs\bst\bti\bit\btu\but\bti\bio\bon\bn
+
+ If a word contains any of the characters `*', `?', `[' or
+ `{' or begins with the character `~', then that word is a
+ candidate for filename substitution, also known as `glob-
+ bing'. This word is then regarded as a pattern, and
+ replaced with an alphabetically sorted list of file names
+ which match the pattern. In a list of words specifying
+ filename substitution it is an error for no pattern to match
+ an existing file name, but it is not required for each pat-
+ tern to match. Only the metacharacters `*', `?' and `['
+ imply pattern matching, the characters `~' and `{' being
+ more akin to abbreviations.
+
+ In matching filenames, the character `.' at the beginning of
+ a filename or immediately following a `/', as well as the
+ character `/' must be matched explicitly. The character `*'
+ matches any string of characters, including the null string.
+ The character `?' matches any single character. The
+ sequence `[...]' matches any one of the characters enclosed.
+ Within `[...]', a pair of characters separated by `-'
+ matches any character lexically between the two.
+
+ The character `~' at the beginning of a filename is used to
+ refer to home directories. Standing alone, i.e. `~' it
+ expands to the invokers home directory as reflected in the
+ value of the variable _\bh_\bo_\bm_\be. When followed by a name consist-
+ ing of letters, digits and `-' characters the shell searches
+ for a user with that name and substitutes their home direc-
+ tory; thus `~ken' might expand to `/usr/ken' and
+ `~ken/chmach' to `/usr/ken/chmach'. If the character `~' is
+ followed by a character other than a letter or `/' or
+ appears not at the beginning of a word, it is left undis-
+ turbed.
+
+ The metanotation `a{b,c,d}e' is a shorthand for `abe ace
+ ade'. Left to right order is preserved, with results of
+ matches being sorted separately at a low level to preserve
+
+
+
+Printed 7/9/88 April 24, 1988 11
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ this order. This construct may be nested. Thus
+ `~source/s1/{oldls,ls}.c' expands to `/usr/source/s1/oldls.c
+ /usr/source/s1/ls.c' whether or not these files exist
+ without any chance of error if the home directory for
+ `source' is `/usr/source'. Similarly `../{memo,*box}' might
+ expand to `../memo ../box ../mbox'. (Note that `memo' was
+ not sorted with the results of matching `*box'.) As a spe-
+ cial case `{', `}' and `{}' are passed undisturbed.
+
+ I\bIn\bnp\bpu\but\bt/\b/o\bou\but\btp\bpu\but\bt
+
+ The standard input and standard output of a command may be
+ redirected with the following syntax:
+
+ < name
+ Open file _\bn_\ba_\bm_\be (which is first variable, command and
+ filename expanded) as the standard input.
+
+ << word
+ Read the shell input up to a line which is identical to
+ _\bw_\bo_\br_\bd. _\bW_\bo_\br_\bd is not subjected to variable, filename or
+ command substitution, and each input line is compared
+ to _\bw_\bo_\br_\bd before any substitutions are done on this input
+ line. Unless a quoting `\', `"', `'' or ``' appears in
+ _\bw_\bo_\br_\bd variable and command substitution is performed on
+ the intervening lines, allowing `\' to quote `$', `\'
+ and ``'. Commands which are substituted have all
+ blanks, tabs, and newlines preserved, except for the
+ final newline which is dropped. The resultant text is
+ placed in an anonymous temporary file which is given to
+ the command as standard input.
+
+ > name
+ >! name
+ >& name
+ >&! name
+ The file _\bn_\ba_\bm_\be is used as standard output. If the file
+ does not exist then it is created; if the file exists,
+ its is truncated, its previous contents being lost.
+
+ If the variable _\bn_\bo_\bc_\bl_\bo_\bb_\bb_\be_\br is set, then the file must
+ not exist or be a character special file (e.g. a termi-
+ nal or `/dev/null') or an error results. This helps
+ prevent accidental destruction of files. In this case
+ the `!' forms can be used and suppress this check.
+
+ The forms involving `&' route the diagnostic output
+ into the specified file as well as the standard output.
+ _\bN_\ba_\bm_\be is expanded in the same way as `<' input filenames
+ are.
+
+
+
+
+
+Printed 7/9/88 April 24, 1988 12
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ >> name
+ >>& name
+ >>! name
+ >>&! name
+ Uses file _\bn_\ba_\bm_\be as standard output like `>' but places
+ output at the end of the file. If the variable
+ _\bn_\bo_\bc_\bl_\bo_\bb_\bb_\be_\br is set, then it is an error for the file not
+ to exist unless one of the `!' forms is given. Other-
+ wise similar to `>'.
+
+ A command receives the environment in which the shell was
+ invoked as modified by the input-output parameters and the
+ presence of the command in a pipeline. Thus, unlike some
+ previous shells, commands run from a file of shell commands
+ have no access to the text of the commands by default;
+ rather they receive the original standard input of the
+ shell. The `<<' mechanism should be used to present inline
+ data. This permits shell command scripts to function as
+ components of pipelines and allows the shell to block read
+ its input. Note that the default standard input for a com-
+ mand run detached is n\bno\bot\bt modified to be the empty file
+ `/dev/null'; rather the standard input remains as the origi-
+ nal standard input of the shell. If this is a terminal and
+ if the process attempts to read from the terminal, then the
+ process will block and the user will be notified (see J\bJo\bob\bbs\bs
+ above).
+
+ Diagnostic output may be directed through a pipe with the
+ standard output. Simply use the form `|&' rather than just
+ `|'.
+
+ E\bEx\bxp\bpr\bre\bes\bss\bsi\bio\bon\bns\bs
+
+ A number of the builtin commands (to be described subse-
+ quently) take expressions, in which the operators are simi-
+ lar to those of C, with the same precedence. These expres-
+ sions appear in the @, _\be_\bx_\bi_\bt, _\bi_\bf, and _\bw_\bh_\bi_\bl_\be commands. The
+ following operators are available:
+
+ || && | ^ & == != =~ !~ <= >= < > << >>
+ + - * / % ! ~ ( )
+
+ Here the precedence increases to the right, `==' `!=' `=~'
+ and `!~', `<=' `>=' `<' and `>', `<<' and `>>', `+' and `-',
+ `*' `/' and `%' being, in groups, at the same level. The
+ `==' `!=' `=~' and `!~' operators compare their arguments as
+ strings; all others operate on numbers. The operators `=~'
+ and `!~' are like `!=' and `==' except that the right hand
+ side is a _\bp_\ba_\bt_\bt_\be_\br_\bn (containing, e.g. `*'s, `?'s and instances
+ of `[...]') against which the left hand operand is matched.
+ This reduces the need for use of the _\bs_\bw_\bi_\bt_\bc_\bh statement in
+ shell scripts when all that is really needed is pattern
+
+
+
+Printed 7/9/88 April 24, 1988 13
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ matching.
+
+ Strings which begin with `0' are considered octal numbers.
+ Null or missing arguments are considered `0'. The result of
+ all expressions are strings, which represent decimal
+ numbers. It is important to note that no two components of
+ an expression can appear in the same word; except when adja-
+ cent to components of expressions which are syntactically
+ significant to the parser (`&' `|' `<' `>' `(' `)') they
+ should be surrounded by spaces.
+
+ Also available in expressions as primitive operands are com-
+ mand executions enclosed in `{' and `}' and file enquiries
+ of the form `-_\bl name' where _\bl is one of:
+
+ r read access
+ w write access
+ x execute access
+ e existence
+ o ownership
+ z zero size
+ f plain file
+ d directory
+
+ The specified name is command and filename expanded and then
+ tested to see if it has the specified relationship to the
+ real user. If the file does not exist or is inaccessible
+ then all enquiries return false, i.e. `0'. Command execu-
+ tions succeed, returning true, i.e. `1', if the command
+ exits with status 0, otherwise they fail, returning false,
+ i.e. `0'. If more detailed status information is required
+ then the command should be executed outside of an expression
+ and the variable _\bs_\bt_\ba_\bt_\bu_\bs examined.
+
+ C\bCo\bon\bnt\btr\bro\bol\bl f\bfl\blo\bow\bw
+
+ The shell contains a number of commands which can be used to
+ regulate the flow of control in command files (shell
+ scripts) and (in limited but useful ways) from terminal
+ input. These commands all operate by forcing the shell to
+ reread or skip in its input and, due to the implementation,
+ restrict the placement of some of the commands.
+
+ The _\bf_\bo_\br_\be_\ba_\bc_\bh, _\bs_\bw_\bi_\bt_\bc_\bh, and _\bw_\bh_\bi_\bl_\be statements, as well as the
+ _\bi_\bf-_\bt_\bh_\be_\bn-_\be_\bl_\bs_\be form of the _\bi_\bf statement require that the major
+ keywords appear in a single simple command on an input line
+ as shown below.
+
+ If the shell's input is not seekable, the shell buffers up
+ input whenever a loop is being read and performs seeks in
+ this internal buffer to accomplish the rereading implied by
+ the loop. (To the extent that this allows, backward goto's
+
+
+
+Printed 7/9/88 April 24, 1988 14
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ will succeed on non-seekable inputs.)
+
+ B\bBu\bui\bil\blt\bti\bin\bn c\bco\bom\bmm\bma\ban\bnd\bds\bs
+
+ Builtin commands are executed within the shell. If a buil-
+ tin command occurs as any component of a pipeline except the
+ last then it is executed in a subshell.
+
+ a\bal\bli\bia\bas\bs
+ a\bal\bli\bia\bas\bs name
+ a\bal\bli\bia\bas\bs name wordlist
+ The first form prints all aliases. The second form
+ prints the alias for name. The final form assigns the
+ specified _\bw_\bo_\br_\bd_\bl_\bi_\bs_\bt as the alias of _\bn_\ba_\bm_\be; _\bw_\bo_\br_\bd_\bl_\bi_\bs_\bt is
+ command and filename substituted. _\bN_\ba_\bm_\be is not allowed
+ to be _\ba_\bl_\bi_\ba_\bs or _\bu_\bn_\ba_\bl_\bi_\ba_\bs.
+
+ a\bal\bll\blo\boc\bc
+ Shows the amount of dynamic memory acquired, broken
+ down into used and free memory. With an argument shows
+ the number of free and used blocks in each size
+ category. The categories start at size 8 and double at
+ each step. This command's output may vary across sys-
+ tem types, since systems other than the VAX may use a
+ different memory allocator.
+
+ b\bbg\bg
+ b\bbg\bg %\b%job ...
+ Puts the current or specified jobs into the background,
+ continuing them if they were stopped.
+
+ b\bbr\bre\bea\bak\bk
+ Causes execution to resume after the _\be_\bn_\bd of the nearest
+ enclosing _\bf_\bo_\br_\be_\ba_\bc_\bh or _\bw_\bh_\bi_\bl_\be. The remaining commands on
+ the current line are executed. Multi-level breaks are
+ thus possible by writing them all on one line.
+
+ b\bbr\bre\bea\bak\bks\bsw\bw
+ Causes a break from a _\bs_\bw_\bi_\bt_\bc_\bh, resuming after the _\be_\bn_\bd_\bs_\bw.
+
+ c\bca\bas\bse\be label:
+ A label in a _\bs_\bw_\bi_\bt_\bc_\bh statement as discussed below.
+
+ c\bcd\bd
+ c\bcd\bd name
+ c\bch\bhd\bdi\bir\br
+ c\bch\bhd\bdi\bir\br name
+ Change the shell's working directory to directory _\bn_\ba_\bm_\be.
+ If no argument is given then change to the home direc-
+ tory of the user.
+ If _\bn_\ba_\bm_\be is not found as a subdirectory of the current
+ directory (and does not begin with `/', `./' or `../'),
+
+
+
+Printed 7/9/88 April 24, 1988 15
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ then each component of the variable _\bc_\bd_\bp_\ba_\bt_\bh is checked
+ to see if it has a subdirectory _\bn_\ba_\bm_\be. Finally, if all
+ else fails but _\bn_\ba_\bm_\be is a shell variable whose value
+ begins with `/', then this is tried to see if it is a
+ directory.
+
+ c\bco\bon\bnt\bti\bin\bnu\bue\be
+ Continue execution of the nearest enclosing _\bw_\bh_\bi_\bl_\be or
+ _\bf_\bo_\br_\be_\ba_\bc_\bh. The rest of the commands on the current line
+ are executed.
+
+ d\bde\bef\bfa\bau\bul\blt\bt:\b:
+ Labels the default case in a _\bs_\bw_\bi_\bt_\bc_\bh statement. The
+ default should come after all _\bc_\ba_\bs_\be labels.
+
+ d\bdi\bir\brs\bs
+ Prints the directory stack; the top of the stack is at
+ the left, the first directory in the stack being the
+ current directory.
+
+ e\bec\bch\bho\bo wordlist
+ e\bec\bch\bho\bo -\b-n\bn wordlist
+ The specified words are written to the shells standard
+ output, separated by spaces, and terminated with a new-
+ line unless the -\b-n\bn option is specified.
+
+ e\bel\bls\bse\be
+ e\ben\bnd\bd
+ e\ben\bnd\bdi\bif\bf
+ e\ben\bnd\bds\bsw\bw
+ See the description of the _\bf_\bo_\br_\be_\ba_\bc_\bh, _\bi_\bf, _\bs_\bw_\bi_\bt_\bc_\bh, and
+ _\bw_\bh_\bi_\bl_\be statements below.
+
+ e\bev\bva\bal\bl arg ...
+ (As in _\bs_\bh(1).) The arguments are read as input to the
+ shell and the resulting command(s) executed in the con-
+ text of the current shell. This is usually used to
+ execute commands generated as the result of command or
+ variable substitution, since parsing occurs before
+ these substitutions. See _\bt_\bs_\be_\bt(1) for an example of
+ using _\be_\bv_\ba_\bl.
+
+ e\bex\bxe\bec\bc command
+ The specified command is executed in place of the
+ current shell.
+
+ e\bex\bxi\bit\bt
+ e\bex\bxi\bit\bt(expr)
+ The shell exits either with the value of the _\bs_\bt_\ba_\bt_\bu_\bs
+ variable (first form) or with the value of the speci-
+ fied _\be_\bx_\bp_\br (second form).
+
+
+
+
+Printed 7/9/88 April 24, 1988 16
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ f\bfg\bg
+ f\bfg\bg %\b%job ...
+ Brings the current or specified jobs into the fore-
+ ground, continuing them if they were stopped.
+
+ f\bfo\bor\bre\bea\bac\bch\bh name (wordlist)
+ ...
+ e\ben\bnd\bd
+ The variable _\bn_\ba_\bm_\be is successively set to each member of
+ _\bw_\bo_\br_\bd_\bl_\bi_\bs_\bt and the sequence of commands between this com-
+ mand and the matching _\be_\bn_\bd are executed. (Both _\bf_\bo_\br_\be_\ba_\bc_\bh
+ and _\be_\bn_\bd must appear alone on separate lines.)
+
+ The builtin command _\bc_\bo_\bn_\bt_\bi_\bn_\bu_\be may be used to continue
+ the loop prematurely and the builtin command _\bb_\br_\be_\ba_\bk to
+ terminate it prematurely. When this command is read
+ from the terminal, the loop is read up once prompting
+ with `?' before any statements in the loop are exe-
+ cuted. If you make a mistake typing in a loop at the
+ terminal you can rub it out.
+
+ g\bgl\blo\bob\bb wordlist
+ Like _\be_\bc_\bh_\bo but no `\' escapes are recognized and words
+ are delimited by null characters in the output. Useful
+ for programs which wish to use the shell to filename
+ expand a list of words.
+
+ g\bgo\bot\bto\bo word
+ The specified _\bw_\bo_\br_\bd is filename and command expanded to
+ yield a string of the form `label'. The shell rewinds
+ its input as much as possible and searches for a line
+ of the form `label:' possibly preceded by blanks or
+ tabs. Execution continues after the specified line.
+
+ h\bha\bas\bsh\bhs\bst\bta\bat\bt
+ Print a statistics line indicating how effective the
+ internal hash table has been at locating commands (and
+ avoiding _\be_\bx_\be_\bc's). An _\be_\bx_\be_\bc is attempted for each com-
+ ponent of the _\bp_\ba_\bt_\bh where the hash function indicates a
+ possible hit, and in each component which does not
+ begin with a `/'.
+
+ h\bhi\bis\bst\bto\bor\bry\by
+ h\bhi\bis\bst\bto\bor\bry\by _\bn
+ h\bhi\bis\bst\bto\bor\bry\by -\b-r\br _\bn
+ h\bhi\bis\bst\bto\bor\bry\by -\b-h\bh _\bn
+ Displays the history event list; if _\bn is given only the
+ _\bn most recent events are printed. The -\b-r\br option rev-
+ erses the order of printout to be most recent first
+ rather than oldest first. The -\b-h\bh option causes the
+ history list to be printed without leading numbers.
+ This is used to produce files suitable for sourceing
+
+
+
+Printed 7/9/88 April 24, 1988 17
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ using the -h option to _\bs_\bo_\bu_\br_\bc_\be.
+
+ i\bif\bf (expr) command
+ If the specified expression evaluates true, then the
+ single _\bc_\bo_\bm_\bm_\ba_\bn_\bd with arguments is executed. Variable
+ substitution on _\bc_\bo_\bm_\bm_\ba_\bn_\bd happens early, at the same time
+ it does for the rest of the _\bi_\bf command. _\bC_\bo_\bm_\bm_\ba_\bn_\bd must
+ be a simple command, not a pipeline, a command list, or
+ a parenthesized command list. Input/output redirection
+ occurs even if _\be_\bx_\bp_\br is false, when command is n\bno\bot\bt exe-
+ cuted (this is a bug).
+
+ i\bif\bf (expr) t\bth\bhe\ben\bn
+ ...
+ e\bel\bls\bse\be i\bif\bf (expr2) t\bth\bhe\ben\bn
+ ...
+ e\bel\bls\bse\be
+ ...
+ e\ben\bnd\bdi\bif\bf
+ If the specified _\be_\bx_\bp_\br is true then the commands to the
+ first _\be_\bl_\bs_\be are executed; otherwise if _\be_\bx_\bp_\br_\b2 is true
+ then the commands to the second _\be_\bl_\bs_\be are executed, etc.
+ Any number of _\be_\bl_\bs_\be-_\bi_\bf pairs are possible; only one
+ _\be_\bn_\bd_\bi_\bf is needed. The _\be_\bl_\bs_\be part is likewise optional.
+ (The words _\be_\bl_\bs_\be and _\be_\bn_\bd_\bi_\bf must appear at the beginning
+ of input lines; the _\bi_\bf must appear alone on its input
+ line or after an _\be_\bl_\bs_\be.)
+
+ j\bjo\bob\bbs\bs
+ j\bjo\bob\bbs\bs -\b-l\bl
+ Lists the active jobs; given the -\b-l\bl options lists pro-
+ cess id's in addition to the normal information.
+
+ k\bki\bil\bll\bl %\b%job
+ k\bki\bil\bll\bl -\b-sig %\b%job ...
+ k\bki\bil\bll\bl pid
+ k\bki\bil\bll\bl -\b-sig pid ...
+ k\bki\bil\bll\bl -\b-l\bl
+ Sends either the TERM (terminate) signal or the speci-
+ fied signal to the specified jobs or processes. Sig-
+ nals are either given by number or by names (as given
+ in /_\bu_\bs_\br/_\bi_\bn_\bc_\bl_\bu_\bd_\be/_\bs_\bi_\bg_\bn_\ba_\bl._\bh, stripped of the prefix
+ ``SIG''). The signal names are listed by ``kill -l''.
+ There is no default, saying just `kill' does not send a
+ signal to the current job. If the signal being sent is
+ TERM (terminate) or HUP (hangup), then the job or pro-
+ cess will be sent a CONT (continue) signal as well.
+
+ l\bli\bim\bmi\bit\bt
+ l\bli\bim\bmi\bit\bt _\br_\be_\bs_\bo_\bu_\br_\bc_\be
+ l\bli\bim\bmi\bit\bt _\br_\be_\bs_\bo_\bu_\br_\bc_\be _\bm_\ba_\bx_\bi_\bm_\bu_\bm-_\bu_\bs_\be
+
+
+
+
+Printed 7/9/88 April 24, 1988 18
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ l\bli\bim\bmi\bit\bt -\b-h\bh
+ l\bli\bim\bmi\bit\bt -\b-h\bh _\br_\be_\bs_\bo_\bu_\br_\bc_\be
+ l\bli\bim\bmi\bit\bt -\b-h\bh _\br_\be_\bs_\bo_\bu_\br_\bc_\be _\bm_\ba_\bx_\bi_\bm_\bu_\bm-_\bu_\bs_\be
+ Limits the consumption by the current process and each
+ process it creates to not individually exceed _\bm_\ba_\bx_\bi_\bm_\bu_\bm-
+ _\bu_\bs_\be on the specified _\br_\be_\bs_\bo_\bu_\br_\bc_\be. If no _\bm_\ba_\bx_\bi_\bm_\bu_\bm-_\bu_\bs_\be is
+ given, then the current limit is printed; if no
+ _\br_\be_\bs_\bo_\bu_\br_\bc_\be is given, then all limitations are given. If
+ the -\b-h\bh flag is given, the hard limits are used instead
+ of the current limits. The hard limits impose a ceil-
+ ing on the values of the current limits. Only the
+ super-user may raise the hard limits, but a user may
+ lower or raise the current limits within the legal
+ range.
+
+ Resources controllable currently include _\bc_\bp_\bu_\bt_\bi_\bm_\be (the
+ maximum number of cpu-seconds to be used by each pro-
+ cess), _\bf_\bi_\bl_\be_\bs_\bi_\bz_\be (the largest single file which can be
+ created), _\bd_\ba_\bt_\ba_\bs_\bi_\bz_\be (the maximum growth of the
+ data+stack region via _\bs_\bb_\br_\bk(2) beyond the end of the
+ program text), _\bs_\bt_\ba_\bc_\bk_\bs_\bi_\bz_\be (the maximum size of the
+ automatically-extended stack region), and _\bc_\bo_\br_\be_\bd_\bu_\bm_\bp_\bs_\bi_\bz_\be
+ (the size of the largest core dump that will be
+ created).
+
+ The _\bm_\ba_\bx_\bi_\bm_\bu_\bm-_\bu_\bs_\be may be given as a (floating point or
+ integer) number followed by a scale factor. For all
+ limits other than _\bc_\bp_\bu_\bt_\bi_\bm_\be the default scale is `k' or
+ `kilobytes' (1024 bytes); a scale factor of `m' or
+ `megabytes' may also be used. For _\bc_\bp_\bu_\bt_\bi_\bm_\be the default
+ scaling is `seconds', while `m' for minutes or `h' for
+ hours, or a time of the form `mm:ss' giving minutes and
+ seconds may be used.
+
+ For both _\br_\be_\bs_\bo_\bu_\br_\bc_\be names and scale factors, unambiguous
+ prefixes of the names suffice.
+
+ l\blo\bog\bgi\bin\bn
+ Terminate a login shell, replacing it with an instance
+ of /\b/b\bbi\bin\bn/\b/l\blo\bog\bgi\bin\bn.\b. This is one way to log off, included for
+ compatibility with _\bs_\bh(1).
+
+ l\blo\bog\bgo\bou\but\bt
+ Terminate a login shell. Especially useful if
+ _\bi_\bg_\bn_\bo_\br_\be_\be_\bo_\bf is set.
+
+ n\bni\bic\bce\be
+ n\bni\bic\bce\be +number
+ n\bni\bic\bce\be command
+ n\bni\bic\bce\be +number command
+ The first form sets the scheduling priority for this
+ shell to 4. The second form sets the priority to the
+
+
+
+Printed 7/9/88 April 24, 1988 19
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ given number. The final two forms run command at
+ priority 4 and _\bn_\bu_\bm_\bb_\be_\br respectively. The greater the
+ number, the less cpu the process will get. The super-
+ user may specify negative priority by using `nice
+ -number ...'. Command is always executed in a sub-
+ shell, and the restrictions placed on commands in sim-
+ ple _\bi_\bf statements apply.
+
+ n\bno\boh\bhu\bup\bp
+ n\bno\boh\bhu\bup\bp command
+ The first form can be used in shell scripts to cause
+ hangups to be ignored for the remainder of the script.
+ The second form causes the specified command to be run
+ with hangups ignored. All processes detached with `&'
+ are effectively _\bn_\bo_\bh_\bu_\bp'_\be_\bd.
+
+ n\bno\bot\bti\bif\bfy\by
+ n\bno\bot\bti\bif\bfy\by %\b%job ...
+ Causes the shell to notify the user asynchronously when
+ the status of the current or specified jobs changes;
+ normally notification is presented before a prompt.
+ This is automatic if the shell variable _\bn_\bo_\bt_\bi_\bf_\by is set.
+
+ o\bon\bni\bin\bnt\btr\br
+ o\bon\bni\bin\bnt\btr\br -
+ o\bon\bni\bin\bnt\btr\br label
+ Control the action of the shell on interrupts. The
+ first form restores the default action of the shell on
+ interrupts which is to terminate shell scripts or to
+ return to the terminal command input level. The second
+ form `onintr -' causes all interrupts to be ignored.
+ The final form causes the shell to execute a `goto
+ label' when an interrupt is received or a child process
+ terminates because it was interrupted.
+
+ In any case, if the shell is running detached and
+ interrupts are being ignored, all forms of _\bo_\bn_\bi_\bn_\bt_\br have
+ no meaning and interrupts continue to be ignored by the
+ shell and all invoked commands.
+
+ p\bpo\bop\bpd\bd
+ p\bpo\bop\bpd\bd +n
+ Pops the directory stack, returning to the new top
+ directory. With an argument `+_\bn' discards the _\bnth
+ entry in the stack. The elements of the directory
+ stack are numbered from 0 starting at the top.
+
+ p\bpu\bus\bsh\bhd\bd
+ p\bpu\bus\bsh\bhd\bd name
+ p\bpu\bus\bsh\bhd\bd +n
+ With no arguments, _\bp_\bu_\bs_\bh_\bd exchanges the top two elements
+ of the directory stack. Given a _\bn_\ba_\bm_\be argument, _\bp_\bu_\bs_\bh_\bd
+
+
+
+Printed 7/9/88 April 24, 1988 20
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ changes to the new directory (ala _\bc_\bd) and pushes the
+ old current working directory (as in _\bc_\bs_\bw) onto the
+ directory stack. With a numeric argument, rotates the
+ _\bnth argument of the directory stack around to be the
+ top element and changes to it. The members of the
+ directory stack are numbered from the top starting at
+ 0.
+
+ r\bre\beh\bha\bas\bsh\bh
+ Causes the internal hash table of the contents of the
+ directories in the _\bp_\ba_\bt_\bh variable to be recomputed.
+ This is needed if new commands are added to directories
+ in the _\bp_\ba_\bt_\bh while you are logged in. This should only
+ be necessary if you add commands to one of your own
+ directories, or if a systems programmer changes the
+ contents of one of the system directories.
+
+ r\bre\bep\bpe\bea\bat\bt count command
+ The specified _\bc_\bo_\bm_\bm_\ba_\bn_\bd which is subject to the same res-
+ trictions as the _\bc_\bo_\bm_\bm_\ba_\bn_\bd in the one line _\bi_\bf statement
+ above, is executed _\bc_\bo_\bu_\bn_\bt times. I/O redirections occur
+ exactly once, even if _\bc_\bo_\bu_\bn_\bt is 0.
+
+ s\bse\bet\bt
+ s\bse\bet\bt name
+ s\bse\bet\bt name=word
+ s\bse\bet\bt name[index]=word
+ s\bse\bet\bt name=(wordlist)
+ The first form of the command shows the value of all
+ shell variables. Variables which have other than a
+ single word as value print as a parenthesized word
+ list. The second form sets _\bn_\ba_\bm_\be to the null string.
+ The third form sets _\bn_\ba_\bm_\be to the single _\bw_\bo_\br_\bd. The fourth
+ form sets the _\bi_\bn_\bd_\be_\bx'_\bt_\bh component of name to word; this
+ component must already exist. The final form sets _\bn_\ba_\bm_\be
+ to the list of words in _\bw_\bo_\br_\bd_\bl_\bi_\bs_\bt. In all cases the
+ value is command and filename expanded.
+
+ These arguments may be repeated to set multiple values
+ in a single set command. Note however, that variable
+ expansion happens for all arguments before any setting
+ occurs.
+
+ s\bse\bet\bte\ben\bnv\bv
+ s\bse\bet\bte\ben\bnv\bv name value
+ s\bse\bet\bte\ben\bnv\bv name
+ The first form lists all current environment variables.
+ The last form sets the value of environment variable
+ _\bn_\ba_\bm_\be to be _\bv_\ba_\bl_\bu_\be, a single string. The second form
+ sets _\bn_\ba_\bm_\be to an empty string. The most commonly used
+ environment variable USER, TERM, and PATH are automati-
+ cally imported to and exported from the _\bc_\bs_\bh variables
+
+
+
+Printed 7/9/88 April 24, 1988 21
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ _\bu_\bs_\be_\br, _\bt_\be_\br_\bm, and _\bp_\ba_\bt_\bh; there is no need to use _\bs_\be_\bt_\be_\bn_\bv
+ for these.
+
+ s\bsh\bhi\bif\bft\bt
+ s\bsh\bhi\bif\bft\bt variable
+ The members of _\ba_\br_\bg_\bv are shifted to the left, discarding
+ _\ba_\br_\bg_\bv[_\b1]. It is an error for _\ba_\br_\bg_\bv not to be set or to
+ have less than one word as value. The second form per-
+ forms the same function on the specified variable.
+
+ s\bso\bou\bur\brc\bce\be name
+ s\bso\bou\bur\brc\bce\be -\b-h\bh name
+ The shell reads commands from _\bn_\ba_\bm_\be. _\bS_\bo_\bu_\br_\bc_\be commands may
+ be nested; if they are nested too deeply the shell may
+ run out of file descriptors. An error in a _\bs_\bo_\bu_\br_\bc_\be at
+ any level terminates all nested _\bs_\bo_\bu_\br_\bc_\be commands. Nor-
+ mally input during _\bs_\bo_\bu_\br_\bc_\be commands is not placed on the
+ history list; the -h option causes the commands to be
+ placed in the history list without being executed.
+
+ s\bst\bto\bop\bp
+ s\bst\bto\bop\bp %\b%job ...
+ Stops the current or specified job which is executing
+ in the background.
+
+ s\bsu\bus\bsp\bpe\ben\bnd\bd
+ Causes the shell to stop in its tracks, much as if it
+ had been sent a stop signal with ^\b^Z\bZ. This is most
+ often used to stop shells started by _\bs_\bu(1).
+
+ s\bsw\bwi\bit\btc\bch\bh (string)
+ c\bca\bas\bse\be str1:
+ ...
+ b\bbr\bre\bea\bak\bks\bsw\bw
+ ...
+ d\bde\bef\bfa\bau\bul\blt\bt:\b:
+ ...
+ b\bbr\bre\bea\bak\bks\bsw\bw
+ e\ben\bnd\bds\bsw\bw
+ Each case label is successively matched, against the
+ specified _\bs_\bt_\br_\bi_\bn_\bg which is first command and filename
+ expanded. The file metacharacters `*', `?' and `[...]'
+ may be used in the case labels, which are variable
+ expanded. If none of the labels match before a
+ `default' label is found, then the execution begins
+ after the default label. Each case label and the
+ default label must appear at the beginning of a line.
+ The command _\bb_\br_\be_\ba_\bk_\bs_\bw causes execution to continue after
+ the _\be_\bn_\bd_\bs_\bw. Otherwise control may fall through case
+ labels and default labels as in C. If no label matches
+ and there is no default, execution continues after the
+ _\be_\bn_\bd_\bs_\bw.
+
+
+
+Printed 7/9/88 April 24, 1988 22
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ t\bti\bim\bme\be
+ t\bti\bim\bme\be command
+ With no argument, a summary of time used by this shell
+ and its children is printed. If arguments are given
+ the specified simple command is timed and a time sum-
+ mary as described under the _\bt_\bi_\bm_\be variable is printed.
+ If necessary, an extra shell is created to print the
+ time statistic when the command completes.
+
+ u\bum\bma\bas\bsk\bk
+ u\bum\bma\bas\bsk\bk value
+ The file creation mask is displayed (first form) or set
+ to the specified value (second form). The mask is
+ given in octal. Common values for the mask are 002
+ giving all access to the group and read and execute
+ access to others or 022 giving all access except no
+ write access for users in the group or others.
+
+ u\bun\bna\bal\bli\bia\bas\bs pattern
+ All aliases whose names match the specified pattern are
+ discarded. Thus all aliases are removed by `unalias
+ *'. It is not an error for nothing to be _\bu_\bn_\ba_\bl_\bi_\ba_\bs_\be_\bd.
+
+ u\bun\bnh\bha\bas\bsh\bh
+ Use of the internal hash table to speed location of
+ executed programs is disabled.
+
+ u\bun\bnl\bli\bim\bmi\bit\bt
+ u\bun\bnl\bli\bim\bmi\bit\bt _\br_\be_\bs_\bo_\bu_\br_\bc_\be
+ u\bun\bnl\bli\bim\bmi\bit\bt -\b-h\bh
+ u\bun\bnl\bli\bim\bmi\bit\bt -\b-h\bh _\br_\be_\bs_\bo_\bu_\br_\bc_\be
+ Removes the limitation on _\br_\be_\bs_\bo_\bu_\br_\bc_\be. If no _\br_\be_\bs_\bo_\bu_\br_\bc_\be is
+ specified, then all _\br_\be_\bs_\bo_\bu_\br_\bc_\be limitations are removed.
+ If -\b-h\bh is given, the corresponding hard limits are
+ removed. Only the super-user may do this.
+
+ u\bun\bns\bse\bet\bt pattern
+ All variables whose names match the specified pattern
+ are removed. Thus all variables are removed by `unset
+ *'; this has noticeably distasteful side-effects. It
+ is not an error for nothing to be _\bu_\bn_\bs_\be_\bt.
+
+ u\bun\bns\bse\bet\bte\ben\bnv\bv pattern
+ Removes all variables whose name match the specified
+ pattern from the environment. See also the _\bs_\be_\bt_\be_\bn_\bv com-
+ mand above and _\bp_\br_\bi_\bn_\bt_\be_\bn_\bv(1).
+
+ w\bwa\bai\bit\bt
+ All background jobs are waited for. It the shell is
+ interactive, then an interrupt can disrupt the wait, at
+ which time the shell prints names and job numbers of
+ all jobs known to be outstanding.
+
+
+
+Printed 7/9/88 April 24, 1988 23
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ w\bwh\bhi\bil\ble\be (expr)
+ ...
+ e\ben\bnd\bd
+ While the specified expression evaluates non-zero, the
+ commands between the _\bw_\bh_\bi_\bl_\be and the matching end are
+ evaluated. _\bB_\br_\be_\ba_\bk and _\bc_\bo_\bn_\bt_\bi_\bn_\bu_\be may be used to terminate
+ or continue the loop prematurely. (The _\bw_\bh_\bi_\bl_\be and _\be_\bn_\bd
+ must appear alone on their input lines.) Prompting
+ occurs here the first time through the loop as for the
+ _\bf_\bo_\br_\be_\ba_\bc_\bh statement if the input is a terminal.
+
+ %\b%job
+ Brings the specified job into the foreground.
+
+ %\b%job &\b&
+ Continues the specified job in the background.
+
+ @\b@
+ @\b@ name = expr
+ @\b@ name[index] = expr
+ The first form prints the values of all the shell vari-
+ ables. The second form sets the specified _\bn_\ba_\bm_\be to the
+ value of _\be_\bx_\bp_\br. If the expression contains `<', `>', `&'
+ or `|' then at least this part of the expression must
+ be placed within `(' `)'. The third form assigns the
+ value of _\be_\bx_\bp_\br to the _\bi_\bn_\bd_\be_\bx'_\bt_\bh argument of _\bn_\ba_\bm_\be. Both
+ _\bn_\ba_\bm_\be and its _\bi_\bn_\bd_\be_\bx'_\bt_\bh component must already exist.
+
+ The operators `*=', `+=', etc are available as in C.
+ The space separating the name from the assignment
+ operator is optional. Spaces are, however, mandatory
+ in separating components of _\be_\bx_\bp_\br which would otherwise
+ be single words.
+
+ Special postfix `++' and `--' operators increment and
+ decrement _\bn_\ba_\bm_\be respectively, i.e. `@ i++'.
+
+ P\bPr\bre\be-\b-d\bde\bef\bfi\bin\bne\bed\bd a\ban\bnd\bd e\ben\bnv\bvi\bir\bro\bon\bnm\bme\ben\bnt\bt v\bva\bar\bri\bia\bab\bbl\ble\bes\bs
+
+ The following variables have special meaning to the shell.
+ Of these, _\ba_\br_\bg_\bv, _\bc_\bw_\bd, _\bh_\bo_\bm_\be, _\bp_\ba_\bt_\bh, _\bp_\br_\bo_\bm_\bp_\bt, _\bs_\bh_\be_\bl_\bl and _\bs_\bt_\ba_\bt_\bu_\bs
+ are always set by the shell. Except for _\bc_\bw_\bd and _\bs_\bt_\ba_\bt_\bu_\bs this
+ setting occurs only at initialization; these variables will
+ not then be modified unless this is done explicitly by the
+ user.
+
+ This shell copies the environment variable USER into the
+ variable _\bu_\bs_\be_\br, TERM into _\bt_\be_\br_\bm, and HOME into _\bh_\bo_\bm_\be, and
+ copies these back into the environment whenever the normal
+ shell variables are reset. The environment variable PATH is
+ likewise handled; it is not necessary to worry about its
+ setting other than in the file ._\bc_\bs_\bh_\br_\bc as inferior _\bc_\bs_\bh
+
+
+
+Printed 7/9/88 April 24, 1988 24
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ processes will import the definition of _\bp_\ba_\bt_\bh from the
+ environment, and re-export it if you then change it.
+
+ a\bar\brg\bgv\bv Set to the arguments to the shell, it is from
+ this variable that positional parameters are
+ substituted, i.e. `$1' is replaced by
+ `$argv[1]', etc.
+
+ c\bcd\bdp\bpa\bat\bth\bh Gives a list of alternate directories
+ searched to find subdirectories in _\bc_\bh_\bd_\bi_\br com-
+ mands.
+
+ c\bcw\bwd\bd The full pathname of the current directory.
+
+ e\bec\bch\bho\bo Set when the -\b-x\bx command line option is given.
+ Causes each command and its arguments to be
+ echoed just before it is executed. For non-
+ builtin commands all expansions occur before
+ echoing. Builtin commands are echoed before
+ command and filename substitution, since
+ these substitutions are then done selec-
+ tively.
+
+ f\bfi\bil\ble\bec\bc Enable file name completion.
+
+ h\bhi\bis\bst\btc\bch\bha\bar\brs\bs Can be given a string value to change the
+ characters used in history substitution. The
+ first character of its value is used as the
+ history substitution character, replacing the
+ default character !. The second character of
+ its value replaces the character |\b^ in quick
+ substitutions.
+
+ h\bhi\bis\bst\bto\bor\bry\by Can be given a numeric value to control the
+ size of the history list. Any command which
+ has been referenced in this many events will
+ not be discarded. Too large values of _\bh_\bi_\bs_\b-
+ _\bt_\bo_\br_\by may run the shell out of memory. The
+ last executed command is always saved on the
+ history list.
+
+ h\bho\bom\bme\be The home directory of the invoker, initial-
+ ized from the environment. The filename
+ expansion of `~\b~' refers to this variable.
+
+ i\big\bgn\bno\bor\bre\bee\beo\bof\bf If set the shell ignores end-of-file from
+ input devices which are terminals. This
+ prevents shells from accidentally being
+ killed by control-D's.
+
+ m\bma\bai\bil\bl The files where the shell checks for mail.
+ This is done after each command completion
+
+
+
+Printed 7/9/88 April 24, 1988 25
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ which will result in a prompt, if a specified
+ interval has elapsed. The shell says `You
+ have new mail.' if the file exists with an
+ access time not greater than its modify time.
+
+ If the first word of the value of _\bm_\ba_\bi_\bl is
+ numeric it specifies a different mail check-
+ ing interval, in seconds, than the default,
+ which is 10 minutes.
+
+ If multiple mail files are specified, then
+ the shell says `New mail in _\bn_\ba_\bm_\be' when there
+ is mail in the file _\bn_\ba_\bm_\be.
+
+ n\bno\boc\bcl\blo\bob\bbb\bbe\ber\br As described in the section on _\bI_\bn_\bp_\bu_\bt/_\bo_\bu_\bt_\bp_\bu_\bt,
+ restrictions are placed on output redirection
+ to insure that files are not accidentally
+ destroyed, and that `>>' redirections refer
+ to existing files.
+
+ n\bno\bog\bgl\blo\bob\bb If set, filename expansion is inhibited.
+ This is most useful in shell scripts which
+ are not dealing with filenames, or after a
+ list of filenames has been obtained and
+ further expansions are not desirable.
+
+ n\bno\bon\bno\bom\bma\bat\btc\bch\bh If set, it is not an error for a filename
+ expansion to not match any existing files;
+ rather the primitive pattern is returned. It
+ is still an error for the primitive pattern
+ to be malformed, i.e. `echo [' still gives
+ an error.
+
+ n\bno\bot\bti\bif\bfy\by If set, the shell notifies asynchronously of
+ job completions. The default is to rather
+ present job completions just before printing
+ a prompt.
+
+ p\bpa\bat\bth\bh Each word of the path variable specifies a
+ directory in which commands are to be sought
+ for execution. A null word specifies the
+ current directory. If there is no _\bp_\ba_\bt_\bh vari-
+ able then only full path names will execute.
+ The usual search path is `.', `/bin' and
+ `/usr/bin', but this may vary from system to
+ system. For the super-user the default
+ search path is `/etc', `/bin' and `/usr/bin'.
+ A shell which is given neither the -\b-c\bc nor the
+ -\b-t\bt option will normally hash the contents of
+ the directories in the _\bp_\ba_\bt_\bh variable after
+ reading ._\bc_\bs_\bh_\br_\bc, and each time the _\bp_\ba_\bt_\bh vari-
+ able is reset. If new commands are added to
+
+
+
+Printed 7/9/88 April 24, 1988 26
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ these directories while the shell is active,
+ it may be necessary to give the _\br_\be_\bh_\ba_\bs_\bh or the
+ commands may not be found.
+
+ p\bpr\bro\bom\bmp\bpt\bt The string which is printed before each com-
+ mand is read from an interactive terminal
+ input. If a `!' appears in the string it
+ will be replaced by the current event number
+ unless a preceding `\' is given. Default is
+ `% ', or `# ' for the super-user.
+
+ s\bsa\bav\bve\beh\bhi\bis\bst\bt is given a numeric value to control the
+ number of entries of the history list that
+ are saved in ~/.history when the user logs
+ out. Any command which has been referenced
+ in this many events will be saved. During
+ start up the shell sources ~/.history into
+ the history list enabling history to be saved
+ across logins. Too large values of _\bs_\ba_\bv_\be_\bh_\bi_\bs_\bt
+ will slow down the shell during start up.
+
+ s\bsh\bhe\bel\bll\bl The file in which the shell resides. This is
+ used in forking shells to interpret files
+ which have execute bits set, but which are
+ not executable by the system. (See the
+ description of _\bN_\bo_\bn-_\bb_\bu_\bi_\bl_\bt_\bi_\bn _\bC_\bo_\bm_\bm_\ba_\bn_\bd _\bE_\bx_\be_\bc_\bu_\bt_\bi_\bo_\bn
+ below.) Initialized to the (system-dependent)
+ home of the shell.
+
+ s\bst\bta\bat\btu\bus\bs The status returned by the last command. If
+ it terminated abnormally, then 0200 is added
+ to the status. Builtin commands which fail
+ return exit status `1', all other builtin
+ commands set status `0'.
+
+ t\bti\bim\bme\be Controls automatic timing of commands. If
+ set, then any command which takes more than
+ this many cpu seconds will cause a line giv-
+ ing user, system, and real times and a utili-
+ zation percentage which is the ratio of user
+ plus system times to real time to be printed
+ when it terminates.
+
+ v\bve\ber\brb\bbo\bos\bse\be Set by the -\b-v\bv command line option, causes the
+ words of each command to be printed after
+ history substitution.
+
+ N\bNo\bon\bn-\b-b\bbu\bui\bil\blt\bti\bin\bn c\bco\bom\bmm\bma\ban\bnd\bd e\bex\bxe\bec\bcu\but\bti\bio\bon\bn
+
+ When a command to be executed is found to not be a builtin
+ command the shell attempts to execute the command via
+ _\be_\bx_\be_\bc_\bv_\be(2). Each word in the variable _\bp_\ba_\bt_\bh names a directory
+
+
+
+Printed 7/9/88 April 24, 1988 27
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ from which the shell will attempt to execute the command.
+ If it is given neither a -\b-c\bc nor a -\b-t\bt option, the shell will
+ hash the names in these directories into an internal table
+ so that it will only try an _\be_\bx_\be_\bc in a directory if there is
+ a possibility that the command resides there. This greatly
+ speeds command location when a large number of directories
+ are present in the search path. If this mechanism has been
+ turned off (via _\bu_\bn_\bh_\ba_\bs_\bh), or if the shell was given a -\b-c\bc or
+ -\b-t\bt argument, and in any case for each directory component of
+ _\bp_\ba_\bt_\bh which does not begin with a `/', the shell concatenates
+ with the given command name to form a path name of a file
+ which it then attempts to execute.
+
+ Parenthesized commands are always executed in a subshell.
+ Thus `(cd ; pwd) ; pwd' prints the _\bh_\bo_\bm_\be directory; leaving
+ you where you were (printing this after the home directory),
+ while `cd ; pwd' leaves you in the _\bh_\bo_\bm_\be directory.
+ Parenthesized commands are most often used to prevent _\bc_\bh_\bd_\bi_\br
+ from affecting the current shell.
+
+ If the file has execute permissions but is not an executable
+ binary to the system, then it is assumed to be a file con-
+ taining shell commands and a new shell is spawned to read
+ it.
+
+ If there is an _\ba_\bl_\bi_\ba_\bs for _\bs_\bh_\be_\bl_\bl then the words of the alias
+ will be prepended to the argument list to form the shell
+ command. The first word of the _\ba_\bl_\bi_\ba_\bs should be the full
+ path name of the shell (e.g. `$shell'). Note that this is a
+ special, late occurring, case of _\ba_\bl_\bi_\ba_\bs substitution, and
+ only allows words to be prepended to the argument list
+ without modification.
+
+ A\bAr\brg\bgu\bum\bme\ben\bnt\bt l\bli\bis\bst\bt p\bpr\bro\boc\bce\bes\bss\bsi\bin\bng\bg
+
+ If argument 0 to the shell is `-' then this is a login
+ shell. The flag arguments are interpreted as follows:
+
+ -\b-b\bb This flag forces a ``break'' from option processing,
+ causing any further shell arguments to be treated as
+ non-option arguments. The remaining arguments will not
+ be interpreted as shell options. This may be used to
+ pass options to a shell script without confusion or
+ possible subterfuge. The shell will not run a set-user
+ ID script without this option.
+
+ -\b-c\bc Commands are read from the (single) following argument
+ which must be present. Any remaining arguments are
+ placed in _\ba_\br_\bg_\bv.
+
+ -\b-e\be The shell exits if any invoked command terminates
+ abnormally or yields a non-zero exit status.
+
+
+
+Printed 7/9/88 April 24, 1988 28
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ -\b-f\bf The shell will start faster, because it will neither
+ search for nor execute commands from the file `.cshrc'
+ in the invoker's home directory.
+
+ -\b-i\bi The shell is interactive and prompts for its top-level
+ input, even if it appears to not be a terminal. Shells
+ are interactive without this option if their inputs and
+ outputs are terminals.
+
+ -\b-n\bn Commands are parsed, but not executed. This aids in
+ syntactic checking of shell scripts.
+
+ -\b-s\bs Command input is taken from the standard input.
+
+ -\b-t\bt A single line of input is read and executed. A `\' may
+ be used to escape the newline at the end of this line
+ and continue onto another line.
+
+ -\b-v\bv Causes the _\bv_\be_\br_\bb_\bo_\bs_\be variable to be set, with the effect
+ that command input is echoed after history substitu-
+ tion.
+
+ -\b-x\bx Causes the _\be_\bc_\bh_\bo variable to be set, so that commands
+ are echoed immediately before execution.
+
+ -\b-V\bV Causes the _\bv_\be_\br_\bb_\bo_\bs_\be variable to be set even before
+ `.cshrc' is executed.
+
+ -\b-X\bX Is to -\b-x\bx as -\b-V\bV is to -\b-v\bv.\b.
+
+ After processing of flag arguments, if arguments remain but
+ none of the -\b-c\bc,\b, -\b-i\bi,\b, -\b-s\bs,\b, or -\b-t\bt options was given, the first
+ argument is taken as the name of a file of commands to be
+ executed. The shell opens this file, and saves its name for
+ possible resubstitution by `$0'. Since many systems use
+ either the standard version 6 or version 7 shells whose
+ shell scripts are not compatible with this shell, the shell
+ will execute such a `standard' shell if the first character
+ of a script is not a `#', i.e. if the script does not start
+ with a comment. Remaining arguments initialize the variable
+ _\ba_\br_\bg_\bv.
+
+ S\bSi\big\bgn\bna\bal\bl h\bha\ban\bnd\bdl\bli\bin\bng\bg
+
+ The shell normally ignores _\bq_\bu_\bi_\bt signals. Jobs running
+ detached (either by `&' or the _\bb_\bg or %\b%.\b..\b..\b. &\b& commands) are
+ immune to signals generated from the keyboard, including
+ hangups. Other signals have the values which the shell
+ inherited from its parent. The shells handling of inter-
+ rupts and terminate signals in shell scripts can be con-
+ trolled by _\bo_\bn_\bi_\bn_\bt_\br. Login shells catch the _\bt_\be_\br_\bm_\bi_\bn_\ba_\bt_\be signal;
+ otherwise this signal is passed on to children from the
+
+
+
+Printed 7/9/88 April 24, 1988 29
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ state in the shell's parent. In no case are interrupts
+ allowed when a login shell is reading the file `.logout'.
+
+A\bAU\bUT\bTH\bHO\bOR\bR
+ William Joy. Job control and directory stack features first
+ implemented by J.E. Kulp of I.I.A.S.A, Laxenburg, Austria,
+ with different syntax than that used now. File name comple-
+ tion code written by Ken Greer, HP Labs.
+
+F\bFI\bIL\bLE\bES\bS
+ ~/.cshrc Read at beginning of execution by each shell.
+ ~/.login Read by login shell, after `.cshrc' at login.
+ ~/.logout Read by login shell, at logout.
+ /bin/sh Standard shell, for shell scripts not starting with a `#'.
+ /tmp/sh* Temporary file for `<<'.
+ /etc/passwd Source of home directories for `~name'.
+
+L\bLI\bIM\bMI\bIT\bTA\bAT\bTI\bIO\bON\bNS\bS
+ Words can be no longer than 1024 characters. The system
+ limits argument lists to 10240 characters. The number of
+ arguments to a command which involves filename expansion is
+ limited to 1/6'th the number of characters allowed in an
+ argument list. Command substitutions may substitute no more
+ characters than are allowed in an argument list. To detect
+ looping, the shell restricts the number of _\ba_\bl_\bi_\ba_\bs substitu-
+ tions on a single line to 20.
+
+S\bSE\bEE\bE A\bAL\bLS\bSO\bO
+ sh(1), access(2), execve(2), fork(2), killpg(2), pipe(2),
+ sigvec(2), umask(2), setrlimit(2), wait(2), tty(4),
+ a.out(5), environ(7), `An introduction to the C shell'
+
+B\bBU\bUG\bGS\bS
+ When a command is restarted from a stop, the shell prints
+ the directory it started in if this is different from the
+ current directory; this can be misleading (i.e. wrong) as
+ the job may have changed directories internally.
+
+ Shell builtin functions are not stoppable/restartable. Com-
+ mand sequences of the form `a ; b ; c' are also not handled
+ gracefully when stopping is attempted. If you suspend `b',
+ the shell will then immediately execute `c'. This is espe-
+ cially noticeable if this expansion results from an _\ba_\bl_\bi_\ba_\bs.
+ It suffices to place the sequence of commands in ()'s to
+ force it to a subshell, i.e. `( a ; b ; c )'.
+
+ Control over tty output after processes are started is prim-
+ itive; perhaps this will inspire someone to work on a good
+ virtual terminal interface. In a virtual terminal interface
+ much more interesting things could be done with output con-
+ trol.
+
+
+
+
+Printed 7/9/88 April 24, 1988 30
+
+
+
+
+
+
+CSH(1) UNIX Programmer's Manual CSH(1)
+
+
+
+ Alias substitution is most often used to clumsily simulate
+ shell procedures; shell procedures should be provided rather
+ than aliases.
+
+ Commands within loops, prompted for by `?', are not placed
+ in the _\bh_\bi_\bs_\bt_\bo_\br_\by list. Control structure should be parsed
+ rather than being recognized as built-in commands. This
+ would allow control commands to be placed anywhere, to be
+ combined with `|', and to be used with `&' and `;' metasyn-
+ tax.
+
+ It should be possible to use the `:' modifiers on the output
+ of command substitutions. All and more than one `:' modif-
+ ier should be allowed on `$' substitutions.
+
+ The way the f\bfi\bil\ble\bec\bc facility is implemented is ugly and expen-
+ sive.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Printed 7/9/88 April 24, 1988 31
+
+
+
projects / unix-history / commitdiff