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3.4 Testing Files

Problem

As part of a script execution, you want to test the existence of a file, or test for various file attributes.

Solution

Use the shell's 'file test operators' which are somewhat analogous to DCL's F$PARSE() and F$FILE_ATTRIBUTES() lexical functions.

Discussion

The Korn shell supplies a variety of file test operators which can be used to answer basic questions about a file and it's attributes. Here's an example:

    input='myfile.txt';
    if [ -e $input ]
    then echo "$input file already exists";
    else echo "no such file: $input";
    fi;

Some of the basic file tests operators include:

-d file - TRUE, if file exists and is a directory.
-e file - TRUE, if file exists.
-f file - TRUE, if file exists and is an ordinary file.
-r file - TRUE, if file exists and is readable by current process.
-s file - TRUE, if file exists and has size greater than 0 (zero).
-w file - TRUE, if file exists and is writable by current process.

See the ksh man page for a complete list.

3.4 Testing Files

Problem

Solution

Discussion

See Also