centos man page for expr

EXPR(1) 							   User Commands							   EXPR(1)

NAME
       expr - evaluate expressions

SYNOPSIS
       expr EXPRESSION
       expr OPTION

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 lexicograph-
       ical.  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.

       GNU coreutils online help: <http://www.gnu.org/software/coreutils/> Report expr translation bugs to <http://translationproject.org/team/>

AUTHOR
       Written by Mike Parker, James Youngman, and Paul Eggert.

COPYRIGHT
       Copyright (C) 2013 Free Software Foundation, Inc.  License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
       This is free software: you are free to change and redistribute it.  There is NO WARRANTY, to the extent permitted by law.

SEE ALSO
       The full documentation for expr is maintained as a Texinfo manual.  If the info and expr programs are properly installed at your site,  the
       command

	      info coreutils 'expr invocation'

       should give you access to the complete manual.

GNU coreutils 8.22						     June 2014								   EXPR(1)