1.\" -*- nroff -*- 2.\" 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 without 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.\" 31.\" $FreeBSD: src/bin/expr/expr.1,v 1.9.2.4 2003/05/16 22:55:19 keramida Exp $ 32.\" $DragonFly: src/bin/expr/expr.1,v 1.2 2003/06/17 04:22:50 dillon Exp $ 33.\" 34.Dd May 10, 2002 35.Dt EXPR 1 36.Os 37.Sh NAME 38.Nm expr 39.Nd evaluate expression 40.Sh SYNOPSIS 41.Nm 42.Ar expression 43.Sh DESCRIPTION 44The 45.Nm 46utility evaluates 47.Ar expression 48and writes the result on standard output. 49.Pp 50All operators and operands must be passed as separate arguments. 51Several of the operators have special meaning to command interpreters 52and must therefore be quoted appropriately. 53All integer operands are interpreted in base 10. 54.Pp 55Arithmetic operations are performed using signed integer math. 56.Pp 57Operators are listed below in order of increasing precedence; all 58are left-associative. 59Operators with equal precedence are grouped within { } symbols. 60.Bl -tag -width indent 61.It Ar expr1 Li | Ar expr2 62Return the evaluation of 63.Ar expr1 64if it is neither an empty string nor zero; 65otherwise, returns the evaluation of 66.Ar expr2 . 67.It Ar expr1 Li & Ar expr2 68Return the evaluation of 69.Ar expr1 70if neither expression evaluates to an empty string or zero; 71otherwise, returns zero. 72.It Ar expr1 Li "{=, >, >=, <, <=, !=}" Ar expr2 73Return the results of integer comparison if both arguments are integers; 74otherwise, returns the results of string comparison using the locale-specific 75collation sequence. 76The result of each comparison is 1 if the specified relation is true, 77or 0 if the relation is false. 78.It Ar expr1 Li "{+, -}" Ar expr2 79Return the results of addition or subtraction of integer-valued arguments. 80.It Ar expr1 Li "{*, /, %}" Ar expr2 81Return the results of multiplication, integer division, or remainder of integer-valued arguments. 82.It Ar expr1 Li : Ar expr2 83The 84.Dq \&: 85operator matches 86.Ar expr1 87against 88.Ar expr2 , 89which must be a regular expression. The regular expression is anchored 90to the beginning of the string with an implicit 91.Dq ^ . 92.Pp 93If the match succeeds and the pattern contains at least one regular 94expression subexpression 95.Dq "\e(...\e)" , 96the string corresponding to 97.Dq "\e1" 98is returned; 99otherwise the matching operator returns the number of characters matched. 100If the match fails and the pattern contains a regular expression subexpression 101the null string is returned; 102otherwise 0. 103.El 104.Pp 105Parentheses are used for grouping in the usual manner. 106.Sh EXAMPLES 107.Bl -enum 108.It 109The following example adds one to the variable a. 110.Dl a=`expr $a + 1` 111.It 112The following example returns the filename portion of a pathname stored 113in variable a. The // characters act to eliminate ambiguity with the 114division operator. 115.Dl expr "//$a" Li : '.*/\e(.*\e)' 116.It 117The following example returns the number of characters in variable a. 118.Dl expr $a Li : '.*' 119.El 120.Sh DIAGNOSTICS 121The 122.Nm 123utility exits with one of the following values: 124.Bl -tag -width indent -compact 125.It 0 126the expression is neither an empty string nor 0. 127.It 1 128the expression is an empty string or 0. 129.It 2 130the expression is invalid. 131.El 132.Sh SEE ALSO 133.Xr sh 1 , 134.Xr test 1 135.Sh STANDARDS 136The 137.Nm 138utility conforms to 139.St -p1003.2 . 140