Then run the following command: bash file-checker.shĪfter running this command, the text /root/demo.txt exists. After your file is saved, press ctrl + x to exit the "nano" editor. Just press "enter" to agree with the name that's already there. You'll see a message asking for the File Name to Write. Now you understand what the script does and the purpose of the test command. This prints a message saying that the file does not exist. The if statement sees this "failure" status and skips to the else section, executing the code there, which is echo "$TARGET_FILE does not exist.". If the test command does not find the file, it returns a non-zero status. This prints a message saying that the file exists. The if statement sees this "success" status and executes the code in the then section, which is echo "$TARGET_FILE exists.". If it finds that the file exists, it returns a status of 0. Test is a command that evaluates the condition given to it and returns a status. So when we say the -f flag checks if the file is a "regular file", we mean it checks if the file is a typical data file, not a directory or some other type of special file. Similarly, there are other special types of files, like symbolic links, sockets, and device files, which have specific functions in the operating system. For instance, a directory is technically a type of file, but it's not a regular file - it's a special file that contains a list of other files. Note: Regular files are different from other types of files that exist in Unix-like systems. The -f flag checks if "$TARGET_FILE" is a regular file. This uses the built-in test command to check if the file specified by TARGET_FILE exists. The condition we're testing in this script is test -f "$TARGET_FILE". The purpose of this statement is to test a certain condition and perform different actions depending on whether the condition is true or false. Next, we have an if.then.else conditional statement. In this case, TARGET_FILE is a string containing the path to the file we want to check. # Use an if-else statement to check if the file exists.īefore we run this file, let's take a look at the script we've written:įirst, we define a variable named TARGET_FILE. # Define the path to the target file that we're going to check Next, add the following script in the editor: #!/bin/bash This means we can run our script without making it executable.Īfter running the above script, you should see the "nano" text editor in your terminal, as shown below: In most Linux distributions, this directory is included in the system's command path. Note: While you're free to create the file-checker.sh file in any directory of your choice, we're placing it in the /usr/local/bin directory for a specific reason. Run the following command to create a file named file-checker.sh in the /usr/local/bin directory and open it in the "nano" text editor: nano /usr/local/bin/file-checker.sh You’ll see the file path printed on your terminal, as shown below: Run the following command: realpath demo.txt Now, let’s identify the full path of this file, which we'll need for our scripts in the upcoming sections. Run the following command to create a file named demo.txt (inside any directory you prefer): touch /root/demo.txt Create the file we want to check the existence of.Check if a File Exists in Bash Using the test Commandīefore we learn how to use the test command, we need to do two things: Best of all, you won't need to go through the hassle of installing any additional software- everything you need is already set up and ready to use. You also need a text editor, such as "nano" or "vim", which come pre-installed by default in many Unix-like operating systems.įor the purpose of this blog post, I'll be using KodeKloud’s Ubuntu playground, which lets you access a pre-installed Ubuntu operating system in just one click. To try out the scripts in this blog post, you need access to a Bash shell. In this blog post, we'll explore four different methods to check if a file exists in Bash. In your Bash scripting journey, you’ll likely come across many scenarios where you must verify the existence of a file before performing any operation on it. If not, your script may not work as expected. It's important to ensure that the file exists before you try to write to it. Let's say you're creating a Bash script to save some data in a file.
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