File operators

There is a special class of C-shell operator that lets you test the properties of a file. A file operator is used in comparison expressions of the form if (file_operator file) then. A list of file operators is tabulated below.

The most common usage is to test for a file's existence. The following only runs cleanup if the first argument is an existing file.

File operators
Operator	True if:
-d	file is a directory
-e	file exists
-f	file is ordinary
-o	you are the owner of the file
-r	file is readable by you
-w	file is writable by you
-x	file is executable by you
-z	file is empty

     # Check that the file given by the first
     # argument exists before attempting to
     # use it.
     if ( -e $1 ) then
        cleanup $1
     endif

Here are some other examples.

     # Remove any empty directories.
     if ( -d $file && -z $file ) then
        rmdir $file

     # Give execute access to text files with a .csh extension.
     else if ( $file:e == "csh" && -f $file ) then
        chmod +x $file
     endif