Using the shorter syntax, you would write the following command. Let’s say that you want to check if the “/etc” directory exists for example. In order to check if a directory exists in Bash using shorter forms, specify the “-d” option in brackets and append the command that you want to run if it succeeds. In some cases, you may be interested in checking if a directory exists or not directly in your Bash shell. $ /etc exists on your filesystem Check Directory Existence using shorter forms When executing this script, you would get the following output Output In order to check its existence, you would write the following Bash script #!/bin/bash if ]Įcho "$DIRECTORY exists on your filesystem."Īs an example, let’s say that you want to check with Bash if the directory /etc exists on your system. In order to check if a directory exists in Bash, you have to use the “-d” option and specify the directory name to be checked. ] || echo "This file does not exist!" Check If Directory Exists To test if a file does not exist using the “||” operator, simply check if it exists using the “-f” flag and specify the command to run if it fails. The “||” operator will execute the command on the right if and only if the command on the left fails (i.e exits with a status greater than zero). Note that it is also possible to check if a file does not exist using the “||” operator. Similarly, you can use shorter forms if you want to quickly check if a file does not exist directly in your terminal.
if ]Įcho " does not exist on your filesystem." In order to check if a file does not exist using Bash, you have to use the “!” symbol followed by the “-f” option and the file that you want to check. On the other hand, you may want to check if a file does not exist on your filesystem. In order to check if multiple files exist in Bash, use the “-f” flag and specify the files to be checked separated by the “&” operator. In some cases, you may want to check if multiple files exist on your filesystem or not. Protip : you can use “echo $” in order to see the exit status of the latest command run Checking multiple files In this case, the “&” syntax will check if the exit status of the command on the left is equal to zero : if this is the case, it will execute the command on the right, otherwise it won’t execute it. When you run a command on Bash, it always exits with an error status : 0 for error and numbers greater than 0 for errors (1, 2. In numeric syntax, it is very similar to the general syntax where we provide a collection of numbers.Shorter forms are closely related to exit statuses. Every item will be assigned to the variable named $VAR like below and this variable named $VAR can be used inside the for loop book. Every number in the list will be iterated inside the for loop one by one.
We will provide numbers as a list and iterate over given list.
In this tutorial, we will look at how to use for loop to iterate over files and directories in Linux. Linux system administrators generally use for loop to iterate over files and folder. for loop is one of the most useful of them. Bash provides a lot of useful programming functionalities.