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 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, James Youngman, and Paul Eggert.

REPORTING BUGS

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

COPYRIGHT

       Copyright © 2017 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

       Full documentation at: <http://www.gnu.org/software/coreutils/expr>
       or available locally via: info '(coreutils) expr invocation'