Test on file types question

[pjb]

I get inconsistent results when running a file test command with single brackets:

if [ -s <filename> ]


When I use double brackets, it works:

if [[ -s <filename> ]]


What is the difference?

 

[olded]

Hi:

From the Solaris 7 man page:

A conditional expression is used with the [[ compound
command to test attributes of files and to compare strings. Word splitting and file name generation are not performed on the words between [[ and ]]. Each expression can be constructed from one or more of the following unary or binary expressions:


-a file True, if file exists.
.
.
-s file True, if file exists and has size greater than zero.
# unquote

The [ is a replacment for test. The following
fragments are equivalent:

if [ $x -lt $y ]; then

if test $x -lt $y ; then

Regards,

Ed

 

[Annihilannic]

[[ is an extension introduced in the Korn shell, so if you are using the Bourne shell it won't work.

Annihilannic.