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

.\" 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.
.\"
.\" $Header: /b/source/CVS/src/bin/expr/expr.1,v 1.1 1993/07/20 20:16:26 jtc 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 lexical comparison.
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 begining of  the string with an invisible 
.Dq ^ ,
therefore
.Dq ^
is not a special character.
.Pp
If the pattern contains at lest 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. 
.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
.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
is expected to be 
.St -p1003.2
compatible.
Commit	Line	Data
4a42d607 C	1	.\" Copyright (c) 1993 Winning Strategies, Inc.
	2	.\" All rights reserved.
	3	.\"
	4	.\" Redistribution and use in source and binary forms, with or without
	5	.\" modification, are permitted provided that the following conditions
	6	.\" are met:
	7	.\" 1. Redistributions of source code must retain the above copyright
	8	.\" notice, this list of conditions and the following disclaimer.
	9	.\" 2. Redistributions in binary form must reproduce the above copyright
	10	.\" notice, this list of conditions and the following disclaimer in the
	11	.\" documentation and/or other materials provided with the distribution.
	12	.\" 3. All advertising materials mentioning features or use of this software
	13	.\" must display the following acknowledgement:
	14	.\" This product includes software developed by Winning Strategies, Inc.
	15	.\" 4. The name of the author may not be used to endorse or promote products
	16	.\" derived from this software withough specific prior written permission
	17	.\"
	18	.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	19	.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	20	.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	21	.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	22	.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	23	.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	24	.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	25	.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	26	.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	27	.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	28	.\"
	29	.\" $Header: /b/source/CVS/src/bin/expr/expr.1,v 1.1 1993/07/20 20:16:26 jtc Exp $
	30	.\"
	31	.Dd July 3, 1993
	32	.Dt EXPR 1
	33	.Os
	34	.Sh NAME
	35	.Nm expr
	36	.Nd evaluate expression
	37	.Sh SYNOPSIS
	38	.Nm expr
	39	.Ar expression
	40	.Sh DESCRIPTION
	41	The
	42	.Nm expr
	43	utility evaluates
	44	.Ar expression
	45	and writes the result on standard output.
	46	.Pp
	47	All operators are separate arguments to the
	48	.Nm expr
	49	utility.
	50	Characters special to the command interpreter must be escaped.
	51	.Pp
	52	Operators are listed below in order of increasing precidence.
	53	Operators with equal precidence are grouped within { } symbols.
	54	.Bl -tag -width indent
	55	.It Ar expr1 Li \| Ar expr2
	56	Returns the evaluation of
	57	.Ar expr1
	58	if it is neither an empty string nor zero;
	59	otherwise, returns the evaluation of
	60	.Ar expr2 .
	61	.It Ar expr1 Li & Ar expr2
	62	Returns the evaluation of
	63	.Ar expr1
	64	if neither expression evaluates to an empty string or zero;
65	otherwise, returns zero.
66	.It Ar expr1 Li "{=, >, >=, <, <=, !=}" Ar expr2
67	Returns the results of integer comparision if both arguments are integers;
68	otherwise, returns the results of lexical comparison.
69	The result of each comparison is 1 if the specified relation is true,
70	or 0 if the relation is false.
71	.It Ar expr1 Li "{+, -}" Ar expr2
72	Returns the results of addition or subtraction of integer-valued arguments.
73	.It Ar expr1 Li "{*, /, %}" Ar expr2
74	Returns the results of multiplication, integer division, or remainder of integer-valued arguments.
75	.It Ar expr1 Li : Ar expr2
76	The
77	.Dq \:
78	operator matches
79	.Ar expr1
80	against
81	.Ar expr2 ,
82	which must be a regular expression. The regular expression is anchored
83	to the begining of the string with an invisible
84	.Dq ^ ,
85	therefore
86	.Dq ^
87	is not a special character.
88	.Pp
89	If the pattern contains at lest one regular expression
90	subexpression
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.
96	.El
97	.Pp
98	Parentheses are used for grouping in the usual manner.
99	.Sh EXAMPLES
100	.Bl -enum
101	.It
102	The following example adds one to the variable a.
103	.Dl a=`expr $a + 1`
104	.It
105	The following example returns the filename portion of a pathname stored
106	in variable a. The // characters act to eliminate ambiguity with the
107	division operator.
108	.Dl expr "//$a" Li : './\e(.\e)'
109	.It
110	The following example returns the number of characters in variable a.
111	.Dl expr $a Li : '.*'
112	.El
113	.Sh DIAGNOSTICS
114	The
115	.Nm expr
116	utility exits with one of the following values:
117	.Bl -tag -width Ds
118	.It 0
119	the expression is neither an empty string nor 0.
120	.It 1
121	the expression is an empty string or 0.
122	.It 2
123	the expression is invalid.
124	.El
125	.Sh STANDARDS
126	The
127	.Nm expr
128	utility
129	is expected to be
130	.St -p1003.2
131	compatible.