Check if a command is executable

Question

How can you check if a command can be executable or not in Linux.

Example:

xeyes

Solution 1

From man bash in the conditional expressions paragraph:

-x file

True if file exists and is executable.

So, you can use:

[ -x /usr/bin/xeyes ] && echo "File is executable" || echo "File is not an executable or does not exist"

Solution 2

If you know the location of where the command binary is kept, just do an ls -l. If you don't know the location first find out location using which command

$ which xeyes
/usr/bin/xeyes

If the command has execute permission ( x ) set, then it is executable.

$ ls -l /usr/bin/

-rw-rw-r-- 1 arushirai arushirai 0 May 23 11:58 123
-rwxrwxr-x 1 arushirai arushirai 0 May 23 11:58 xeyes

The -x <filename> actually checks if the file has execute permission set

Explanation:

THe first column of ls -l shows the permission on file.

-rwxrwxr-x

• r is read permission
• w is write permission
• x is execute permission

-rwxrwxr-x

• 1st bit: tells type of file ( - is for regular file )
• Next 3 bits: owner permission ( rwx : read, write and execute )
• Next 3 bits: group permission ( rwx : read , write and execute )
• Next 3 bits: other permission (r-x : read and execute permission )

For more information on file permissions read: https://wiki.archlinux.org/index.php/File_permissions_and_attributes

Solution 3

If you don't known a path to the command you can use which to check where it is (of course, if you have it in $PATH). If you know a path to command file use if -x /path/to/command statement.

Comments

[cjaphe]

This fails completely when using -x $(which bogus) instead of -x /usr/bin/bogus. For it, which bogus >/dev/null && echo "available" || echo "unavailable" works just fine for me.