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