[unix-history] / usr / src / bin / expr / expr.1

.\"	@(#)expr.1	6.1 (Berkeley) %G%
.\"
.TH EXPR 1 ""
.AT 3
.SH NAME
expr \- evaluate arguments as an expression
.SH SYNOPSIS
.B expr
arg
.B .\|.\|.
.SH DESCRIPTION
The arguments are taken as an expression.
After evaluation, the result is written on the standard output.
Each token of the expression is a separate argument.
.PP
The operators and keywords are listed below.
The list is in order of increasing precedence,
with equal precedence operators grouped.
.TP
.I expr | expr
yields the first
.I expr
if it is neither null nor `0', otherwise
yields the second
.I expr.
.TP
.I expr & expr
yields the first
.I expr
if neither
.I expr
is null or `0', otherwise yields `0'.
.TP
.I expr relop expr
where
.I relop is one of
< <= = != >= >,
yields `1' if the indicated comparison is true, `0' if false.
The comparison is numeric if both
.I expr
are integers, otherwise lexicographic.
.TP
.IR expr " + " expr
.br
.ns
.TP
.IR expr " \- " expr
.br
addition or subtraction of the arguments.
.TP
.IR expr " * " expr
.br
.ns
.TP
.IR expr " / " expr
.br
.ns
.TP
.IR expr " % " expr
.br
multiplication, division, or remainder of the arguments.
.TP
.IR expr " : " expr
The matching operator compares the string first argument
with the regular expression second argument;
regular expression syntax is the same as that of
.IR ed (1).
The
\fB\\(\|.\|.\|.\|\\)\fP
pattern symbols can be used to select a portion of the
first argument.
Otherwise,
the matching operator yields the number of characters matched
(`0' on failure).
.TP
.RI ( " expr " )
parentheses for grouping.
.PP
Examples:
.PP
To add 1 to the Shell variable
.IR a :
.IP
a=\`expr $a + 1\`
.PP
To find the filename part (least significant part)
of the pathname stored in variable
.I a,
which may or may not contain `/':
.IP
expr $a : \'.*/\e(\^.*\e)\' \'\^|\' $a
.LP
Note the quoted Shell metacharacters.
.SH "SEE ALSO"
sh(1), test(1)
.SH DIAGNOSTICS
.I Expr
returns the following exit codes:
.PP
	0	if the expression is neither null nor `0',
.br
	1	if the expression
is null or `0',
.br
	2	for invalid expressions.
Commit	Line	Data
0e1c2e9d	1	.\" @(#)expr.1 6.1 (Berkeley) %G%
b9c0268e	2	.\"
0e1c2e9d	3	.TH EXPR 1 ""
b9c0268e KM	4	.AT 3
	5	.SH NAME
	6	expr \- evaluate arguments as an expression
	7	.SH SYNOPSIS
	8	.B expr
	9	arg
	10	.B .\\|.\\|.
	11	.SH DESCRIPTION
	12	The arguments are taken as an expression.
	13	After evaluation, the result is written on the standard output.
	14	Each token of the expression is a separate argument.
	15	.PP
	16	The operators and keywords are listed below.
	17	The list is in order of increasing precedence,
	18	with equal precedence operators grouped.
	19	.TP
	20	.I expr \| expr
	21	yields the first
	22	.I expr
	23	if it is neither null nor `0', otherwise
	24	yields the second
	25	.I expr.
	26	.TP
	27	.I expr & expr
	28	yields the first
	29	.I expr
	30	if neither
	31	.I expr
	32	is null or `0', otherwise yields `0'.
	33	.TP
	34	.I expr relop expr
	35	where
	36	.I relop is one of
	37	< <= = != >= >,
	38	yields `1' if the indicated comparison is true, `0' if false.
	39	The comparison is numeric if both
	40	.I expr
	41	are integers, otherwise lexicographic.
	42	.TP
	43	.IR expr " + " expr
	44	.br
	45	.ns
	46	.TP
	47	.IR expr " \- " expr
	48	.br
	49	addition or subtraction of the arguments.
	50	.TP
	51	.IR expr " * " expr
	52	.br
	53	.ns
	54	.TP
	55	.IR expr " / " expr
	56	.br
	57	.ns
	58	.TP
	59	.IR expr " % " expr
	60	.br
	61	multiplication, division, or remainder of the arguments.
	62	.TP
	63	.IR expr " : " expr
	64	The matching operator compares the string first argument
	65	with the regular expression second argument;
	66	regular expression syntax is the same as that of
	67	.IR ed (1).
68	The
69	\fB\\(\\|.\\|.\\|.\\|\\)\fP
70	pattern symbols can be used to select a portion of the
71	first argument.
72	Otherwise,
73	the matching operator yields the number of characters matched
74	(`0' on failure).
75	.TP
76	.RI ( " expr " )
77	parentheses for grouping.
78	.PP
79	Examples:
80	.PP
81	To add 1 to the Shell variable
82	.IR a :
83	.IP
84	a=\`expr $a + 1\`
85	.PP
86	To find the filename part (least significant part)
87	of the pathname stored in variable
88	.I a,
89	which may or may not contain `/':
90	.IP
91	expr $a : \'./\e(\^.\e)\' \'\^\|\' $a
92	.LP
93	Note the quoted Shell metacharacters.
94	.SH "SEE ALSO"
95	sh(1), test(1)
96	.SH DIAGNOSTICS
97	.I Expr
98	returns the following exit codes:
99	.PP
100	0 if the expression is neither null nor `0',
101	.br
102	1 if the expression
103	is null or `0',
104	.br
105	2 for invalid expressions.