expr - Unix, Linux Command

NAME

expr - evaluate expressions

SYNOPSIS

expr EXPRESSION
expr OPTION

DESCRIPTION

Tag	Description
--help	display this help and exit
--version
	output version information and exit
Print the value of EXPRESSION to standard output. A blank line below separates increasing precedence groups. EXPRESSION may be:
ARG1 \| ARG2
	ARG1 if it is neither null nor 0, otherwise ARG2
ARG1 & ARG2
	ARG1 if neither argument is null or 0, otherwise 0
ARG1 < ARG2
	ARG1 is less than ARG2
ARG1 <= ARG2
	ARG1 is less than or equal to ARG2
ARG1 = ARG2
	ARG1 is equal to ARG2
ARG1 != ARG2
	ARG1 is unequal to ARG2
ARG1 >= ARG2
	ARG1 is greater than or equal to ARG2
ARG1 > ARG2
	ARG1 is greater than ARG2
ARG1 + ARG2
	arithmetic sum of ARG1 and ARG2
ARG1 - ARG2
	arithmetic difference of ARG1 and ARG2
ARG1 * ARG2
	arithmetic product of ARG1 and ARG2
ARG1 / ARG2
	arithmetic quotient of ARG1 divided by ARG2
ARG1 % ARG2
	arithmetic remainder of ARG1 divided by ARG2
STRING : REGEXP
	anchored pattern match of REGEXP in STRING
match STRING REGEXP
	same as STRING : REGEXP
substr STRING POS LENGTH
	substring of STRING, POS counted from 1
index STRING CHARS
	index in STRING where any CHARS is found, or 0
length STRING
	length of STRING
+ TOKEN
	interpret TOKEN as a string, even if it is a
	keyword like ‘match’ or an operator like ‘/’
( EXPRESSION )
	value of EXPRESSION

Beware that many operators need to be escaped or quoted for shells. Comparisons are arithmetic if both ARGs are numbers, else lexicographical. Pattern matches return the string matched between \( and \) or null; if \( and \) are not used, they return the number of characters matched or 0.

Exit status is 0 if EXPRESSION is neither null nor 0, 1 if EXPRESSION is null or 0, 2 if EXPRESSION is syntactically invalid, and 3 if an error occurred.

AUTHOR

Written by Mike Parker.

REPORTING BUGS

Report bugs to <bug-coreutils@gnu.org>.

COPYRIGHT

Copyright © 2006 Free Software Foundation, Inc.
This is free software. You may redistribute copies of it under the terms of the GNU General Public License <http://www.gnu.org/licenses/gpl.html>. There is NO WARRANTY, to the extent permitted by law.