(coreutils.info)test invocation

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Enter node , (file) or (file)node

16.3 ‘test’: Check file types and compare values
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‘test’ returns a status of 0 (true) or 1 (false) depending on the
evaluation of the conditional expression EXPR.  Each part of the
expression must be a separate argument.

   ‘test’ has file status checks, string operators, and numeric
comparison operators.

   ‘test’ has an alternate form that uses opening and closing square
brackets instead a leading ‘test’.  For example, instead of ‘test -d /’,
you can write ‘[ -d / ]’.  The square brackets must be separate
arguments; for example, ‘[-d /]’ does not have the desired effect.
Since ‘test EXPR’ and ‘[ EXPR ]’ have the same meaning, only the former
form is discussed below.

   Synopses:

     test EXPRESSION
     test
     [ EXPRESSION ]
     [ ]
     [ OPTION

   Due to shell aliases and built-in ‘test’ functions, using an
unadorned ‘test’ interactively or in a script may get you different
functionality than that described here.  Invoke it via ‘env’ (i.e., ‘env
test ...’) to avoid interference from the shell.

   If EXPRESSION is omitted, ‘test’ returns false.  If EXPRESSION is a
single argument, ‘test’ returns false if the argument is null and true
otherwise.  The argument can be any string, including strings like ‘-d’,
‘-1’, ‘--’, ‘--help’, and ‘--version’ that most other programs would
treat as options.  To get help and version information, invoke the
commands ‘[ --help’ and ‘[ --version’, without the usual closing
brackets.  Note: Common options.

   Exit status:

     0 if the expression is true,
     1 if the expression is false,
     2 if an error occurred.

File type tests

-[bcdfhLpSt]

Access permission tests

-[gkruwxOG]

File characteristic tests

-e -s -nt -ot -ef

String tests

-z -n = == !=

Numeric tests

-eq -ne -lt -le -gt -ge

Connectives for test

! -a -o