coreutils: test invocation
1
1 16.3 ‘test’: Check file types and compare values
1 ================================================
1
1 ‘test’ returns a status of 0 (true) or 1 (false) depending on the
1 evaluation of the conditional expression EXPR. Each part of the
1 expression must be a separate argument.
1
1 ‘test’ has file status checks, string operators, and numeric
1 comparison operators.
1
1 ‘test’ has an alternate form that uses opening and closing square
1 brackets instead a leading ‘test’. For example, instead of ‘test -d /’,
1 you can write ‘[ -d / ]’. The square brackets must be separate
1 arguments; for example, ‘[-d /]’ does not have the desired effect.
1 Since ‘test EXPR’ and ‘[ EXPR ]’ have the same meaning, only the former
1 form is discussed below.
1
1 Synopses:
1
1 test EXPRESSION
1 test
1 [ EXPRESSION ]
1 [ ]
1 [ OPTION
1
1 Due to shell aliases and built-in ‘test’ functions, using an
1 unadorned ‘test’ interactively or in a script may get you different
1 functionality than that described here. Invoke it via ‘env’ (i.e., ‘env
1 test ...’) to avoid interference from the shell.
1
1 If EXPRESSION is omitted, ‘test’ returns false. If EXPRESSION is a
1 single argument, ‘test’ returns false if the argument is null and true
1 otherwise. The argument can be any string, including strings like ‘-d’,
1 ‘-1’, ‘--’, ‘--help’, and ‘--version’ that most other programs would
1 treat as options. To get help and version information, invoke the
1 commands ‘[ --help’ and ‘[ --version’, without the usual closing
1 brackets. ⇒Common options.
1
1 Exit status:
1
1 0 if the expression is true,
1 1 if the expression is false,
1 2 if an error occurred.
1
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