Shell Script -x Flag Meaning

Question

I have a #!/bin/sh script that has the following line:

if [ ! -x "$TEST_SLAPD" ]

$TEST_SLAPD is the full path to a .bat file.

I am wondering what the -x flag means in the context of that if statement?

Solution 1

if just checks for result of command following it. [ is not (at least not always) an operator, it's small utility called 'test'.

From its documentation:

-x file
                             True if file exists and is  exe-
                             cutable.   True  indicates  only
                             that the execute flag is on.  If
                             file  is a directory, true indi-
                             cates that file can be searched.

(and yes, ! is obviously negation)

For similar evualation flags, documentation is available here: http://illumos.org/man/1/test

Solution 2

The ! -x conditional means the file or directory doesn't have the executable bit set for the current user. The help is a little less clear about the fact that it applies to directories too, but it says:

$ help test | fgrep -- '-x'
      -x FILE        True if the file is executable by you.

Comments

[Baxter]

If that is returning false and the file is definitely there is it likely a permissions issue with the shell script trying to execute the .bat file?

[Todd A. Jacobs]

@Baxter Yes. That's why -r and -x are often a more useful than just testing for a file's existence with -f.