Basic bash scripting. How to find if a file exists or not.

This simple example shows how to check if a file exists or not.

This is how we do this.

if [ -f "/home/jason/foo" ]

Putting it together in a script makes it simple to verify if the file exists or not.

if [ -f "/home/jason/foo" ]
then
    echo "file does exist."
else
    echo "file not found."
fi

To check if a user exists on your machine, use this syntax.

if getent passwd jason > /dev/null 2>&1; then
    echo "yes the user exists"
else
    echo "No, the user does not exist"
fi

This will check if the user “jason” exists or not.

This type of scripting is very useful if a file needs to be created, and you wish to check if it is already there.