test

PURPOSE

     Evaluates conditional expressions.

SYNOPSIS
     test expr
     [ expr ]


DESCRIPTION

     The test  command evaluates expression and,  if its value
     is true, returns  a zero (true) exit  value; otherwise it
     returns a nonzero (false) exit value; test also returns a
     nonzero exit value if there are no parameters.

     Note:  In the second form of the command, that is the one
     that uses  square brackets ("[ ]"), rather  than the word
     test, the brackets must be surrounded by blanks.

FUNCTIONS

     All the  functions and operators are  separate parameters
     to test.   The following functions are  used to construct
     expression:

     -r file         True if file exists  and has read permis-
                     sion.
     -w file         True if file exists and has write permis-
                     sion.
     -x file         True if file exists  and has execute per-
                     mission.
     -f file         True  if file  exists  and  is a  regular
                     file.
     -d file         True if file exists and is a directory.
     -c file         True if  file exists  and is  a character
                     special file.
     -b file         True  if  file  exists  and  is  a  block
                     special file.
     -p file         True if  file exists and is  a named pipe
                     (FIFO).
     -u file         True if  file exists and  its set-user-ID
                     bit is set.
     -g file         True if file  exists and its set-group-ID
                     bit is set.
     -k file         True if file exists and its sticky bit is
                     set.
     -s file         True  if  file  exists  and  has  a  size
                     greater than zero.
     -t [filedescr]  True   if  the   open   file  with   file
                     descriptor   number   filedescr   (1   by
                     default)  is   associated  with   a  work
                     station device.
     -z s1           True if the length of string s1 is zero.

     -n s1           True if  the length  of the string  s1 is
                     nonzero.
     s1 = s2         True if strings s1 and s2 are identical.
     s1 != s2        True if  strings s1 and s2  are not iden-
                     tical.
     s1              True if s1 is not the null string.
     n1 -eq n2       True if the integers  n1 and n2 are alge-
                     braically equal.  Any  of the comparisons
                     -ne, -gt,  -ge, -lt, and -le  can be used
                     in place of -eq.

     These functions can be combined with the following opera-
     tors:

     !               Unary negation operator.
     -a              Binary AND operator.
     -o              Binary OR operator (-a has higher preced-
                     ence than -o).
     \( expression \)
                     Parentheses for grouping.

EXAMPLES

     1.  To test whether a file exists and is not empty:

           if test ! -s "$1"
           then
              echo $1 does not exist or is empty.
           fi

         If the file specified  by the first positional param-
         eter to the shell procedure does not exist, this dis-
         plays an error message.   If "$1" exists, it displays
         nothing.  Note that there must  be a space between -s
         and the file name.

         The double  quotes around  "$1" ensure that  the test
         will work properly  even if the value of  "$1" is the
         empty string.   If the double quotes  are omitted and
         "$1"  is the  empty string,  test displays  the error
         message "test: parameter expected".

     2.  To do a complex comparison:

           if [ $# -lt 2  -o  ! -s "$1" ]
           then
              exit
           fi

         If the shell procedure was given fewer than two posi-
         tional parameters or the  file specified by "$1" does
         not exist, then this  exits the shell procedure.  The
         special shell variable "$#"  represents the number of
         positional  parameters entered  on  the command  line
         that started this shell procedure.  For more details,
         see "Shell Variables and Command-Line Substitutions."

RELATED INFORMATION

     The following commands:  "find" and  "sh."