[unix-history] / usr / man / man1 / expr.1

.TH EXPR 1 
.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
.IR expr " - " expr
.br
addition or subtraction of the arguments.
.TP
.IR expr " * " expr
.br
.IR expr " / " expr
.br
.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"
ed(1), 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
e6817382 BJ	1	.TH EXPR 1
	2	.SH NAME
	3	expr \- evaluate arguments as an expression
	4	.SH SYNOPSIS
	5	.B expr
	6	arg
	7	.B .\\|.\\|.
	8	.SH DESCRIPTION
	9	The arguments are taken as an expression.
	10	After evaluation, the result is written on the standard output.
	11	Each token of the expression is a separate argument.
	12	.PP
	13	The operators and keywords are listed below.
	14	The list is in order of increasing precedence,
	15	with equal precedence operators grouped.
	16	.TP
	17	.I expr \| expr
	18	yields the first
	19	.I expr
	20	if it is neither null nor `0', otherwise
	21	yields the second
	22	.I expr.
	23	.TP
	24	.I expr & expr
	25	yields the first
	26	.I expr
	27	if neither
	28	.I expr
	29	is null or `0', otherwise yields `0'.
	30	.TP
	31	.I expr relop expr
	32	where
	33	.I relop is one of
	34	< <= = != >= >,
	35	yields `1' if the indicated comparison is true, `0' if false.
	36	The comparison is numeric if both
	37	.I expr
	38	are integers, otherwise lexicographic.
	39	.TP
	40	.IR expr " + " expr
	41	.br
	42	.IR expr " - " expr
	43	.br
	44	addition or subtraction of the arguments.
	45	.TP
	46	.IR expr " * " expr
	47	.br
	48	.IR expr " / " expr
	49	.br
	50	.IR expr " % " expr
	51	.br
	52	multiplication, division, or remainder of the arguments.
	53	.TP
	54	.IR expr " : " expr
	55	The matching operator compares the string first argument
	56	with the regular expression second argument;
	57	regular expression syntax is the same as that of
	58	.IR ed (1).
	59	The
	60	\fB\\(\\|.\\|.\\|.\\|\\)\fP
	61	pattern symbols can be used to select a portion of the
	62	first argument.
	63	Otherwise,
	64	the matching operator yields the number of characters matched
65	(`0' on failure).
66	.TP
67	.RI ( " expr " )
68	parentheses for grouping.
69	.PP
70	Examples:
71	.PP
72	To add 1 to the Shell variable
73	.IR a :
74	.IP
75	a=\`expr $a + 1\`
76	.PP
77	To find the filename part (least significant part)
78	of the pathname stored in variable
79	.I a,
80	which may or may not contain `/':
81	.IP
82	expr $a : \'./\e(\^.\e)\' \'\^\|\' $a
83	.LP
84	Note the quoted Shell metacharacters.
85	.SH "SEE ALSO"
86	ed(1), sh(1), test(1)
87	.SH DIAGNOSTICS
88	.I Expr
89	returns the following exit codes:
90	.PP
91	0 if the expression is neither null nor `0',
92	.br
93	1 if the expression
94	is null or `0',
95	.br
96	2 for invalid expressions.