Check if File or Directory Exists in Bash

Are you writing a Bash script? Checking if a file or directory exists to perform a conditional task is a very common task one might want to achieve. Let's take a look at how that is done in Bash.

The Bash shell has a few built-in file test operators and by using them you can perform these checks.

Let's take a look at an example of checking if the user's .bashrc file exists or not.

#!/usr/bin/env bash

my_file="${HOME}/.bashrc"

if [[ -f "${my_file}" ]]; then
    echo "File '${my_file}' exists."
else
    echo "File '${my_file}' DOES NOT exist."
fi

If I execute this script on my computer, I get the following output:

File '/home/pratham/.bashrc' exists.

To check for a directory, replace the -f operator (which is used for checking if a file exists or not) with the -d operator.

Example 1: A traditional approach

Usually, the Bash built-in test operators are used in combination with the if conditional, like I demonstrated above. This has two advantages. The first advantage is that, by using the -f and -d test operators in the if conditional, you can integrate it in your mind more easily since you probably know how to use if in Bash.

Let's take a look at an example script that checks for the Neovim config file and creates it if it does not exist.

#!/usr/bin/env bash

NVIM_DIR="${HOME}/.configa/nvim"
NVIM_CONF="${NVIM_DIR}/init.lua"

if [[ ! -d "${NVIM_DIR}" ]]; then
    echo "Directory '${NVIM_DIR}' does not exist, creating it..."
    mkdir -p "${NVIM_DIR}"
fi

if [[ ! -f "${NVIM_CONF}" ]]; then
    echo "File '${NVIM_CONF}' does not exist, creating it..."
    echo "vim.opt.number = true" > "${NVIM_CONF}"
    echo "vim.opt.relativenumber = true" >> "${NVIM_CONF}"
fi

echo -e "\nFile contents:"
cat "${NVIM_CONF}"

In this Bash script, I have declared two variables:

• NVIM_DIR: Absolute path to the Neovim configuration directory
• NVIM_CONF: Absolute path to the inital configuration file that Neovim loads

As you can see, I am performing two checks. The first check is to make sure that the Neovim configuration directory exists or not. I intentionally added the logical NOT operator (!) to make the condition opposite. This is me saying "I am only concerned if the directory does not exist".

And, if the Neovim configuration directory does not exist, I create it using the mkdir command.

The second check is a similar check, for the Neovim initial configuration file. Since I am concerned with the check only if the file does not exist, I add the logical NOT operator (!) here too. If the file does not exist, I populate it with two lines using he echo built-in.

Finally, I cat the file's content to the terminal.

Following is the output I get from running this script:

Directory '/home/pratham/.config/nvim' does not exist, creating it...
File '/home/pratham/.config/nvim/init.lua' does not exist, creating it...

File contents:
vim.opt.number = true
vim.opt.relativenumber = true

Example 2: A shortcut ;)

If you know the [ operator (yes, it is an operator!), you will know that there is a shortcut!

Try executing the following script:

#!/usr/bin/env bash

[[ -d "${HOME}" ]] && echo "I have a home directory"
[[ -f "${HOME}/.zshrc" ]] && echo "I am probably using Zsh"
[[ -d "${HOME}/.config/nvim" ]] && echo "Ah, a Neovim user, quite the taste :)"
[[ -f /etc/nixos/configuration.nix ]] || echo "Have you tried NixOS?"

This script is checking the following things:

• If you have a $HOME directory
• If you have a ~/.zshrc file
• If you have a ~/.config/nvim directory
• If you have a /etc/nixos/configuration.nix file

Based on the result and the used logial AND or logical OR operator used with these tests, a statement will be printed to the your terminal.

Following is the output from my computer:

I have a home directory
Ah, a Neovim user, quite the taste :)

Conclusion

The Bash shell has -f and -d file test operators that are used to check the existence of a file and a directory respectively. In this article, I demonstrate its use.