To check whether a file exists in bash, you use the -f operator. For directories, use -d, Example usage: $ mkdir dir $ && echo exists! exists! $ rmdir dir $ && echo exists! $ touch file $ || echo “doesn’t exist.” $ rm file $ || echo “doesn’t exist.” doesn’t exist.
For more information simply execute man test, A note on -e, this test operator checks whether a file exists. While this may seem like a good choice, it’s better to use -f which will return false if the file isn’t a regular file. /dev/null for example is a file but nor a regular file. Having the check return true is undesired in this case.
A note on variables Be sure to quote variables too, once you have a space or any other special character contained in a variable it can have undesired side effects. So when you test for existence of files and directories, wrap the file/dir in double quotes.
Something like will work while the following would fail if there is a space in dir :, You are experiencing a syntax error in the control statements. A bash if clause is structured as following: if,; then, fi Or optional with an else clause: if,; then, else, fi You cannot omit the then clause.
If you wish to only use the else clause you should negate the condition. Resulting in following code: if ; then mkdir “/usr/share/icons/$j/scalable/” fi Here we add an exclamation point ( ! ) to flip the expression’s evaluation. If the expression evaluates to true, the same expression preceded by ! will return false and the other way around.
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Checking the File Type with a Bash Script The -e flag is to check whether the files or the directories exist or not. The -f flag is to check whether the ordinary files (not directories) exist or not. Finally, the -d flag is to check whether this is a directory or not.
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Contents
How to check if a file or directory exists in Bash?
How to Check if a File or Directory Exists in Bash. Many times when writing Shell scripts, you may find yourself in a situation where you need to perform an action based on whether a file exists or not. In Bash, you can use the test command to check whether a file exists and determine the type of the file.
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How do I check if a file is a directory linux?
Check if Directory Exist The operators -d allows you to test whether a file is a directory or not. For example to check whether the /etc/docker directory exist you would use: FILE=/etc/docker if ; then echo ‘$ FILE is a directory.’
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How to test for the presence of a particular file in Bash?
Working with Code Snippets – The previous commands work well for a simple two-line command at a command prompt. You can also use bash with multiple commands. When several commands are strung together, they are called a script, A script is usually saved as a file and executed.
Scripting also uses logical operators to test for a condition, then takes action based on the results of the test. To create a script file, use the Nano editor to open a new file: sudo nano bashtest.sh Enter one of the snippets from below, including the #!/bin/bash identifier. Use Ctrl-o to save the file, then Ctrl-x to exit Nano.
Then, run the script by entering: bash bashtest.sh The following code snippet tests for the presence of a particular file. If the file exists, the script displays File exists on the screen. #!/bin/bash if then echo “File exists” fi This works the same if you’re checking for a directory.
- Just replace the –f option with –d : #!/bin/bash if then echo “File exists” fi This command checks for the directory /tmp/test,
- If it exists, the system displays File exists,
- Conclusion You can now use bash to check if a file and directory exist.
- You can also create simple test scripts as you now understand the functions of a basic bash script file.
Next, you should check out our post on Bash Function, Was this article helpful? Yes No
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How to check if a file is a regular file?
check if a file is a regular file or a directory with find command in Linux – The fourth and final method to check if a file is a regular file or a directory is to use the find command, The “find” command can be used to search for files in a directory hierarchy.
To use the “find” command, you need to specify the path of the directory that you want to search. For example, if you want to search the “/etc” directory for regular files, you would use the following command: find /etc -type f If the “/etc” directory contains regular files, the output of the above command will be a list of all the regular files in the “/etc” directory.
If the “/etc” directory does not contain any regular files, the output of the above command will be an empty list. As you can see, there are four different ways to check if a file is a regular file or a directory in Linux. Each method has its own advantages and disadvantages.
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