Relations for expr (GNU Coreutils 9.0)
16.4.3 Relations for expr
expr supports the usual logical connectives and relations. These have lower precedence than the string and numeric operators (previous sections). Here is the list, lowest-precedence operator first.
Returns its first argument if that is neither null nor zero, otherwise its second argument if it is neither null nor zero, otherwise 0. It does not evaluate its second argument if its first argument is neither null nor zero.
Return its first argument if neither argument is null or zero, otherwise 0. It does not evaluate its second argument if its first argument is null or zero.
< <= = == != >= >’
Compare the arguments and return 1 if the relation is true, 0 otherwise.
==is a synonym for
exprfirst tries to convert both arguments to integers and do a numeric comparison; if either conversion fails, it does a lexicographic comparison using the character collating sequence specified by the