Technology Tales

Adventures in consumer and enterprise technology

TOPIC: SHELL SCRIPT

Checking existence of files and directories on UNIX using shell scripting

23^rd April 2007

Having had a UNIX shell script attempt to copy a non-existent file, I decided to take another look for ways to test the existence of a file. For directory existence checking, I was testing for the return code from the cd command, and I suppose that the ls command might help for files. However, I did find a better way:

if [ -f $filename ]
then
    echo "This filename [$filename] exists"
elif [ -d $dirname ]
then
    echo "This dirname [$dirname] exists"
else
    echo "Neither [$dirname] or [$filename] exist"
fi

The -d and -f flags within the evaluation expressions test for the existence of directories and files, respectively. One gotcha is that those spaces within the brackets are important too, but it is a very way of doing what I wanted.

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