| 1 | .TH GREP 1 "1988 December 13" "GNU Project" |
| 2 | .UC 4 |
| 3 | .SH NAME |
| 4 | grep, egrep \- print lines matching a regular expression |
| 5 | .SH SYNOPSIS |
| 6 | .B grep |
| 7 | [ |
| 8 | .B \-CVbchilnsvwx |
| 9 | ] [ |
| 10 | .BI \- num |
| 11 | ] [ |
| 12 | .B \-AB |
| 13 | .I num |
| 14 | ] [ [ |
| 15 | .B \-e |
| 16 | ] |
| 17 | .I expr |
| 18 | | |
| 19 | .B \-f |
| 20 | .I file |
| 21 | ] [ |
| 22 | .I "files ..." |
| 23 | ] |
| 24 | .SH DESCRIPTION |
| 25 | .I Grep |
| 26 | searches the files listed in the arguments (or standard |
| 27 | input if no files are given) for all lines that contain a match for |
| 28 | the given |
| 29 | .IR expr . |
| 30 | If any lines match, they are printed. |
| 31 | .PP |
| 32 | Also, if any matches were found, |
| 33 | .I grep |
| 34 | will exit with a status of 0, but if no matches were found it will exit |
| 35 | with a status of 1. This is useful for building shell scripts that |
| 36 | use |
| 37 | .I grep |
| 38 | as a condition for, for example, the |
| 39 | .I if |
| 40 | statement. |
| 41 | .PP |
| 42 | When invoked as |
| 43 | .I egrep |
| 44 | the syntax of the |
| 45 | .I expr |
| 46 | is slightly different; See below. |
| 47 | .br |
| 48 | .SH "REGULAR EXPRESSIONS" |
| 49 | .RS 2.5i |
| 50 | .ta 1i; 2i |
| 51 | .sp |
| 52 | .ti -2.0i |
| 53 | (grep) (egrep) (explanation) |
| 54 | .sp |
| 55 | .ti -2.0i |
| 56 | \fIc\fP \fIc\fP a single (non-meta) character matches itself. |
| 57 | .sp |
| 58 | .ti -2.0i |
| 59 | \&. . matches any single character except newline. |
| 60 | .sp |
| 61 | .ti -2.0i |
| 62 | \\? ? postfix operator; preceeding item is optional. |
| 63 | .sp |
| 64 | .ti -2.0i |
| 65 | \(** \(** postfix operator; preceeding item 0 or |
| 66 | more times. |
| 67 | .sp |
| 68 | .ti -2.0i |
| 69 | \\+ + postfix operator; preceeding item 1 or |
| 70 | more times. |
| 71 | .sp |
| 72 | .ti -2.0i |
| 73 | \\| | infix operator; matches either |
| 74 | argument. |
| 75 | .sp |
| 76 | .ti -2.0i |
| 77 | ^ ^ matches the empty string at the beginning of a line. |
| 78 | .sp |
| 79 | .ti -2.0i |
| 80 | $ $ matches the empty string at the end of a line. |
| 81 | .sp |
| 82 | .ti -2.0i |
| 83 | \\< \\< matches the empty string at the beginning of a word. |
| 84 | .sp |
| 85 | .ti -2.0i |
| 86 | \\> \\> matches the empty string at the end of a word. |
| 87 | .sp |
| 88 | .ti -2.0i |
| 89 | [\fIchars\fP] [\fIchars\fP] match any character in the given class; if the |
| 90 | first character after [ is ^, match any character |
| 91 | not in the given class; a range of characters may |
| 92 | be specified by \fIfirst\-last\fP; for example, \\W |
| 93 | (below) is equivalent to the class [^A\-Za\-z0\-9] |
| 94 | .sp |
| 95 | .ti -2.0i |
| 96 | \\( \\) ( ) parentheses are used to override operator precedence. |
| 97 | .sp |
| 98 | .ti -2.0i |
| 99 | \\\fIdigit\fP \\\fIdigit\fP \\\fIn\fP matches a repeat of the text |
| 100 | matched earlier in the regexp by the subexpression inside the nth |
| 101 | opening parenthesis. |
| 102 | .sp |
| 103 | .ti -2.0i |
| 104 | \\ \\ any special character may be preceded |
| 105 | by a backslash to match it literally. |
| 106 | .sp |
| 107 | .ti -2.0i |
| 108 | (the following are for compatibility with GNU Emacs) |
| 109 | .sp |
| 110 | .ti -2.0i |
| 111 | \\b \\b matches the empty string at the edge of a word. |
| 112 | .sp |
| 113 | .ti -2.0i |
| 114 | \\B \\B matches the empty string if not at the edge of a word. |
| 115 | .sp |
| 116 | .ti -2.0i |
| 117 | \\w \\w matches word-constituent characters (letters & digits). |
| 118 | .sp |
| 119 | .ti -2.0i |
| 120 | \\W \\W matches characters that are not word-constituent. |
| 121 | .RE |
| 122 | .PP |
| 123 | Operator precedence is (highest to lowest) ?, \(**, and +, concatenation, |
| 124 | and finally |. All other constructs are syntactically identical to |
| 125 | normal characters. For the truly interested, the file dfa.c describes |
| 126 | (and implements) the exact grammar understood by the parser. |
| 127 | .SH OPTIONS |
| 128 | .TP |
| 129 | .BI \-A " num" |
| 130 | print <num> lines of context after every matching line |
| 131 | .TP |
| 132 | .BI \-B " num" |
| 133 | print |
| 134 | .I num |
| 135 | lines of context before every matching line |
| 136 | .TP |
| 137 | .B \-C |
| 138 | print 2 lines of context on each side of every match |
| 139 | .TP |
| 140 | .BI \- num |
| 141 | print |
| 142 | .I num |
| 143 | lines of context on each side of every match |
| 144 | .TP |
| 145 | .B \-V |
| 146 | print the version number on the diagnostic output |
| 147 | .TP |
| 148 | .B \-b |
| 149 | print every match preceded by its byte offset |
| 150 | .TP |
| 151 | .B \-c |
| 152 | print a total count of matching lines only |
| 153 | .TP |
| 154 | .BI \-e " expr" |
| 155 | search for |
| 156 | .IR expr ; |
| 157 | useful if |
| 158 | .I expr |
| 159 | begins with \- |
| 160 | .TP |
| 161 | .BI \-f " file" |
| 162 | search for the expression contained in |
| 163 | .I file |
| 164 | .TP |
| 165 | .B \-h |
| 166 | don't display filenames on matches |
| 167 | .TP |
| 168 | .B \-i |
| 169 | ignore case difference when comparing strings |
| 170 | .TP |
| 171 | .B \-l |
| 172 | list files containing matches only |
| 173 | .TP |
| 174 | .B \-n |
| 175 | print each match preceded by its line number |
| 176 | .TP |
| 177 | .B \-s |
| 178 | run silently producing no output except error messages |
| 179 | .TP |
| 180 | .B \-v |
| 181 | print only lines that contain no matches for the <expr> |
| 182 | .TP |
| 183 | .B \-w |
| 184 | print only lines where the match is a complete word |
| 185 | .TP |
| 186 | .B \-x |
| 187 | print only lines where the match is a whole line |
| 188 | .SH "SEE ALSO" |
| 189 | emacs(1), ed(1), sh(1), |
| 190 | .I "GNU Emacs Manual" |
| 191 | .SH INCOMPATIBILITIES |
| 192 | The following incompatibilities with UNIX |
| 193 | .I grep |
| 194 | exist: |
| 195 | .PP |
| 196 | .RS 0.5i |
| 197 | The context-dependent meaning of \(** is not quite the same (grep only). |
| 198 | .PP |
| 199 | .B \-b |
| 200 | prints a byte offset instead of a block offset. |
| 201 | .PP |
| 202 | The {\fIm,n\fP} construct of System V grep is not implemented. |
| 203 | .PP |
| 204 | .SH BUGS |
| 205 | GNU \fIe?grep\fP has been thoroughly debugged and tested by several people |
| 206 | over a period of several months; we think it's a reliable beast or we |
| 207 | wouldn't distribute it. If by some fluke of the universe you discover |
| 208 | a bug, send a detailed description (including options, regular |
| 209 | expressions, and a copy of an input file that can reproduce it) to me, |
| 210 | mike@wheaties.ai.mit.edu. |
| 211 | .PP |
| 212 | There is also a newsgroup, gnu.utils.bug, for reporting FSF utility |
| 213 | programs' bugs and fixes; but before reporting something as a bug, |
| 214 | please try to be sure that it really is a bug, not a misunderstanding |
| 215 | or a deliberate feature. Also, include the version number of the |
| 216 | utility program you are running in \fIevery\fR bug report that you |
| 217 | send in. Please do not send anything but bug reports to this |
| 218 | newsgroup. |
| 219 | .PP |
| 220 | .SH AVAILABILITY |
| 221 | .PP |
| 222 | GNU |
| 223 | .I grep |
| 224 | is free; anyone may redistribute copies of |
| 225 | .I grep |
| 226 | to |
| 227 | anyone under the terms stated in the |
| 228 | GNU General Public License, |
| 229 | a copy of which may be found in each copy of |
| 230 | .IR "GNU Emacs" . |
| 231 | See also the comment at the beginning of the source code file grep.c. |
| 232 | .PP |
| 233 | Copies of GNU |
| 234 | .I grep |
| 235 | may sometimes be received packaged with distributions of Unix systems, |
| 236 | but it is never included in the scope of any license covering those |
| 237 | systems. Such inclusion violates the terms on which distribution |
| 238 | is permitted. In fact, the primary purpose of the General Public |
| 239 | License is to prohibit anyone from attaching any other restrictions |
| 240 | to redistribution of any of the Free Software Foundation programs. |
| 241 | .SH AUTHORS |
| 242 | Mike Haertel wrote the deterministic regexp code and the bulk |
| 243 | of the program. |
| 244 | .PP |
| 245 | James A. Woods is responsible for the hybridized search strategy |
| 246 | of using Boyer-Moore-Gosper fixed-string search as a filter |
| 247 | before calling the general regexp matcher. |
| 248 | .PP |
| 249 | Arthur David Olson contributed code that finds fixed strings for |
| 250 | the aforementioned BMG search for a large class of regexps. |
| 251 | .PP |
| 252 | Richard Stallman wrote the backtracking regexp matcher that is |
| 253 | used for \\\fIdigit\fP backreferences, as well as the getopt that |
| 254 | is provided for 4.2BSD sites. The backtracking matcher was |
| 255 | originally written for GNU Emacs. |
| 256 | .PP |
| 257 | D. A. Gwyn wrote the C alloca emulation that is provided so |
| 258 | System V machines can run this program. (Alloca is used only |
| 259 | by RMS' backtracking matcher, and then only rarely, so there |
| 260 | is no loss if your machine doesn't have a "real" alloca.) |
| 261 | .PP |
| 262 | Scott Anderson and Henry Spencer designed the regression tests |
| 263 | used in the "regress" script. |
| 264 | .PP |
| 265 | Paul Placeway wrote the original version of this manual page. |