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.\" 33.Dd August 23, 2016 34.Dt EXPR 1 35.Os 36.Sh NAME 37.Nm expr 38.Nd evaluate expression 39.Sh SYNOPSIS 40.Nm 41.Ar expression 42.Sh DESCRIPTION 43The 44.Nm 45utility evaluates 46.Ar expression 47and writes the result on standard output. 48.Pp 49All operators and operands must be passed as separate arguments. 50Several of the operators have special meaning to command interpreters 51and must therefore be quoted appropriately. 52All integer operands are interpreted in base 10. 53.Pp 54Arithmetic operations are performed using signed integer math. 55.Pp 56Operators are listed below in order of increasing precedence; all 57are left-associative. 58Operators with equal precedence are grouped within { } symbols. 59.Bl -tag -width indent 60.It Ar expr1 | expr2 61Return the evaluation of 62.Ar expr1 63if it is neither an empty string nor zero; 64otherwise, returns the evaluation of 65.Ar expr2 . 66.It Ar expr1 Li & Ar expr2 67Return the evaluation of 68.Ar expr1 69if neither expression evaluates to an empty string or zero; 70otherwise, returns zero. 71.It Ar expr1 Li "{=, >, >=, <, <=, !=}" Ar expr2 72Return the results of integer comparison if both arguments are integers; 73otherwise, returns the results of string comparison using the locale-specific 74collation sequence. 75The result of each comparison is 1 if the specified relation is true, 76or 0 if the relation is false. 77.It Ar expr1 Li "{+, -}" Ar expr2 78Return the results of addition or subtraction of integer-valued arguments. 79.It Ar expr1 Li "{*, /, %}" Ar expr2 80Return the results of multiplication, integer division, or remainder of integer-valued arguments. 81.It Ar expr1 Li : Ar expr2 82The 83.Dq \&: 84operator matches 85.Ar expr1 86against 87.Ar expr2 , 88which must be a regular expression. The regular expression is anchored 89to the beginning of the string with an implicit 90.Dq ^ . 91.Pp 92If the match succeeds and the pattern contains at least one regular 93expression subexpression 94.Dq "\e(...\e)" , 95the string corresponding to 96.Dq "\e1" 97is returned; 98otherwise the matching operator returns the number of characters matched. 99If the match fails and the pattern contains a regular expression subexpression 100the null string is returned; 101otherwise 0. 102.El 103.Pp 104Parentheses are used for grouping in the usual manner. 105.Sh EXIT STATUS 106The 107.Nm 108utility exits with one of the following values: 109.Bl -tag -width indent -compact 110.It 0 111the expression is neither an empty string nor 0. 112.It 1 113the expression is an empty string or 0. 114.It 2 115the expression is invalid. 116.El 117.Sh EXAMPLES 118.Bl -enum 119.It 120The following example adds one to the variable a. 121.Dl a=`expr $a + 1` 122.It 123The following example returns the filename portion of a pathname stored 124in variable a. The // characters act to eliminate ambiguity with the 125division operator. 126.Dl expr "//$a" Li : '.*/\e(.*\e)' 127.It 128The following example returns the number of characters in variable a. 129.Dl expr $a Li : '.*' 130.El 131.Sh SEE ALSO 132.Xr sh 1 , 133.Xr test 1 134.Sh STANDARDS 135The 136.Nm 137utility conforms to 138.St -p1003.2 . 139.Sh HISTORY 140An 141.Nm 142utility first appeared in the Programmer's Workbench (PWB/UNIX). 143A public domain version of 144.Nm 145written by 146.An Pace Willisson 147.Aq Mt pace@blitz.com 148appeared in 149.Bx 386 0.1 . 150.Sh AUTHORS 151Initial implementation by 152.An Pace Willisson 153.Aq Mt pace@blitz.com 154was largely rewritten by 155.An -nosplit 156.An J.T. Conklin 157.Aq Mt jtc@FreeBSD.org . 158