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

.\" -*- nroff -*-
.\"
.\" Copyright (c) 1993 Winning Strategies, Inc.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"      This product includes software developed by Winning Strategies, Inc.
.\" 4. The name of the author may not be used to endorse or promote products
.\"    derived from this software withough specific prior written permission
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
.\"	$Id: expr.1,v 1.3 1994/04/24 01:18:46 jkh Exp $
.\"
.Dd July 3, 1993
.Dt EXPR 1
.Os
.Sh NAME
.Nm expr
.Nd evaluate expression
.Sh SYNOPSIS
.Nm expr
.Ar expression
.Sh DESCRIPTION
The
.Nm expr
utility evaluates 
.Ar expression
and writes the result on standard output.
.Pp
All operators are separate arguments to the
.Nm expr
utility.
Characters special to the command interpreter must be escaped.
.Pp
Operators are listed below in order of increasing precidence.
Operators with equal precidence are grouped within { } symbols.
.Bl -tag -width indent
.It Ar expr1 Li | Ar expr2
Returns the evaluation of 
.Ar expr1 
if it is neither an empty string nor zero;
otherwise, returns the evaluation of
.Ar expr2 .
.It Ar expr1 Li & Ar expr2
Returns the evaluation of
.Ar expr1
if neither expression evaluates to an empty string or zero;
otherwise, returns zero.
.It Ar expr1 Li "{=, >, >=, <, <=, !=}" Ar expr2
Returns the results of integer comparision if both arguments are integers; 
otherwise, returns the results of string comparison using the locale-specific
collation sequence.
The result of each comparison is 1 if the specified relation is true,
or 0 if the relation is false.
.It Ar expr1 Li "{+, -}" Ar expr2
Returns the results of addition or subtraction of integer-valued arguments.
.It Ar expr1 Li "{*, /, %}" Ar expr2
Returns the results of multiplication, integer division, or remainder of integer-valued arguments.
.It Ar expr1 Li : Ar expr2
The 
.Dq \:
operator matches 
.Ar expr1 
against 
.Ar expr2 ,
which must be a regular expression.  The regular expression is anchored
to the beginning of  the string with an implicit 
.Dq ^ .
.Pp
If the match succeeds and the pattern contains at least one regular
expression subexpression 
.Dq "\e(...\e)" , 
the string corresponding to 
.Dq "\e1"
is returned;
otherwise the matching operator returns the number of characters matched. 
If the match fails and the pattern contains a regular expression subexpression
the null string is returned;
otherwise 0.
.El
.Pp
Parentheses are used for grouping in the usual manner.
.Sh EXAMPLES
.Bl -enum
.It 
The following example adds one to the variable a.
.Dl a=`expr $a + 1`
.It
The following example returns the filename portion of a pathname stored
in variable a.  The // characters act to eliminate ambiguity with the
division operator.
.Dl expr "//$a" Li : '.*/\e(.*\e)'
.It
The following example returns the number of characters in variable a.
.Dl expr $a Li : '.*'
.El
.Sh DIAGNOSTICS
The
.Nm expr 
utility exits with one of the following values:
.Bl -tag -width Ds -compact
.It 0
the expression is neither an empty string nor 0.
.It 1
the expression is an empty string or 0.
.It 2
the expression is invalid.
.El
.Sh STANDARDS
The
.Nm expr
utility conforms to
.St -p1003.2 .
Commit	Line	Data
b215e0e7 C	1	.\" -- nroff --
b215e0e7 C	2	.\"
4a42d607 C	3	.\" Copyright (c) 1993 Winning Strategies, Inc.
	4	.\" All rights reserved.
	5	.\"
	6	.\" Redistribution and use in source and binary forms, with or without
	7	.\" modification, are permitted provided that the following conditions
	8	.\" are met:
	9	.\" 1. Redistributions of source code must retain the above copyright
	10	.\" notice, this list of conditions and the following disclaimer.
	11	.\" 2. Redistributions in binary form must reproduce the above copyright
	12	.\" notice, this list of conditions and the following disclaimer in the
	13	.\" documentation and/or other materials provided with the distribution.
	14	.\" 3. All advertising materials mentioning features or use of this software
	15	.\" must display the following acknowledgement:
	16	.\" This product includes software developed by Winning Strategies, Inc.
	17	.\" 4. The name of the author may not be used to endorse or promote products
	18	.\" derived from this software withough specific prior written permission
	19	.\"
	20	.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	21	.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	22	.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	23	.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	24	.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	25	.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	26	.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	27	.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	28	.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	29	.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	30	.\"
c2714ef5	31	.\" $Id: expr.1,v 1.3 1994/04/24 01:18:46 jkh Exp $
4a42d607 C	32	.\"
	33	.Dd July 3, 1993
	34	.Dt EXPR 1
	35	.Os
	36	.Sh NAME
	37	.Nm expr
	38	.Nd evaluate expression
	39	.Sh SYNOPSIS
	40	.Nm expr
	41	.Ar expression
	42	.Sh DESCRIPTION
	43	The
	44	.Nm expr
	45	utility evaluates
	46	.Ar expression
	47	and writes the result on standard output.
	48	.Pp
	49	All operators are separate arguments to the
	50	.Nm expr
	51	utility.
	52	Characters special to the command interpreter must be escaped.
	53	.Pp
	54	Operators are listed below in order of increasing precidence.
	55	Operators with equal precidence are grouped within { } symbols.
	56	.Bl -tag -width indent
	57	.It Ar expr1 Li \| Ar expr2
	58	Returns the evaluation of
	59	.Ar expr1
	60	if it is neither an empty string nor zero;
	61	otherwise, returns the evaluation of
	62	.Ar expr2 .
	63	.It Ar expr1 Li & Ar expr2
	64	Returns the evaluation of
	65	.Ar expr1
	66	if neither expression evaluates to an empty string or zero;
	67	otherwise, returns zero.
	68	.It Ar expr1 Li "{=, >, >=, <, <=, !=}" Ar expr2
	69	Returns the results of integer comparision if both arguments are integers;
b215e0e7 C	70	otherwise, returns the results of string comparison using the locale-specific
b215e0e7 C	71	collation sequence.
4a42d607 C	72	The result of each comparison is 1 if the specified relation is true,
	73	or 0 if the relation is false.
	74	.It Ar expr1 Li "{+, -}" Ar expr2
	75	Returns the results of addition or subtraction of integer-valued arguments.
	76	.It Ar expr1 Li "{*, /, %}" Ar expr2
	77	Returns the results of multiplication, integer division, or remainder of integer-valued arguments.
	78	.It Ar expr1 Li : Ar expr2
	79	The
	80	.Dq \:
	81	operator matches
	82	.Ar expr1
	83	against
	84	.Ar expr2 ,
	85	which must be a regular expression. The regular expression is anchored
c2714ef5	86	to the beginning of the string with an implicit
b215e0e7	87	.Dq ^ .
4a42d607	88	.Pp
b215e0e7 C	89	If the match succeeds and the pattern contains at least one regular
b215e0e7 C	90	expression subexpression
4a42d607 C	91	.Dq "\e(...\e)" ,
	92	the string corresponding to
	93	.Dq "\e1"
	94	is returned;
	95	otherwise the matching operator returns the number of characters matched.
b215e0e7 C	96	If the match fails and the pattern contains a regular expression subexpression
	97	the null string is returned;
	98	otherwise 0.
4a42d607 C	99	.El
	100	.Pp
	101	Parentheses are used for grouping in the usual manner.
	102	.Sh EXAMPLES
	103	.Bl -enum
	104	.It
	105	The following example adds one to the variable a.
	106	.Dl a=`expr $a + 1`
	107	.It
	108	The following example returns the filename portion of a pathname stored
	109	in variable a. The // characters act to eliminate ambiguity with the
	110	division operator.
	111	.Dl expr "//$a" Li : './\e(.\e)'
	112	.It
	113	The following example returns the number of characters in variable a.
	114	.Dl expr $a Li : '.*'
	115	.El
	116	.Sh DIAGNOSTICS
	117	The
	118	.Nm expr
	119	utility exits with one of the following values:
b215e0e7	120	.Bl -tag -width Ds -compact
4a42d607 C	121	.It 0
	122	the expression is neither an empty string nor 0.
	123	.It 1
	124	the expression is an empty string or 0.
	125	.It 2
	126	the expression is invalid.
	127	.El
	128	.Sh STANDARDS
	129	The
	130	.Nm expr
b215e0e7 C	131	utility conforms to
b215e0e7 C	132	.St -p1003.2 .