Info Catalog coreutils: true invocation coreutils: Conditions coreutils: expr invocation

coreutils: test invocation

 
 16.3 ‘test’: Check file types and compare values
 ================================================
 
 ‘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.  ⇒Common options.
 
    Exit status:
 
      0 if the expression is true,
      1 if the expression is false,
      2 if an error occurred.
 

Menu

 
· 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
 

Info Catalog coreutils: true invocation coreutils: Conditions coreutils: expr invocation