Shell Scripting “test”

Here’s a quick reference guide to the tests performed on a variable as part of a shell script.

test expr or [ expr ]

 

Example (if $var is not set to any value)

if [[ -z $var ]]; then

echo “variable has no value”

fi

 

-n file                true if variable has a value set

-z file                true if variable is empty

-L                      true if file is symbolic link

file1 -nt file2      true if file1 newer than file2

file1 -ot file2      true if file1 older than file2

file1 -ef file2      true if file1 and file2 are same device and inode number.

-e file                true if file exists (NOT ON HPUX use f instead)

-x file                true if file is executable

-r file                true if file is readable

-w file               true if file is writable

-f file                 true if file is a regular file

-d directory       true if directory is a directory

-c file                true if character special file

-b file                true if block special file

-p file                true if a named pipe

-u file                true if set UID bit is set

-g file                true if set GID bit is set

-k file                true if sticky bit is set

-s file                true if filesize > 0

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