Category: Bash if directory exists

Bash if directory exists

12.11.2020 By Akihn

By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. It only takes a minute to sign up. I want to write a Bash script, which checks if all directories, stored in an array, exist. If not, the script should create it.

bash if directory exists

Is this a correct way to do it? That will also create intermediary directory components if need be so your array can also be shortened to only include the leaf directories:.

The [[ -d I would suggest adding chownchmodand sort to the script. Using sort will order the shorter paths first.

bash if directory exists

The next change I would make is the -m for mode. If you are a member of GroupA and GroupB, the mkdir command will set the group owner to your default group the first group that shows on an id command. Thus: [[! Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. Bash to check if directory exist. If not create with an array Ask Question.

Asked 5 months ago. Active 5 months ago. Viewed 2k times. The difference is important! Active Oldest Votes. If an array is called without specifying an element or range of elementsit will default to the element with index 0, i. You may want to use mkdir -p to create all subdirectories at once. About TOCTOU: 1 If the directory doesn't exist when checked, mkdir will be executed with both this answer and the check-create sequence.

In both cases the end result is that the directory exists for code to be executed on following lines. The same effect happens if the directory is created with mkdir directly and then it gets erased by some other entity anyway.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

Server Fault is a question and answer site for system and network administrators. It only takes a minute to sign up. Perhaps there's a better way, but I'm writing an application deployment script, and I want to create a directory on a remote server if the directory doesn't exist to place the files. You can use ssh to call a programme on the remote host, test tests for certain conditions. I'd recommend looking at using the RPM mechanism to install your application, rather than writing something home grown, since the problems you'll come across with your own script will almost certainly have already been solved with RPM.

Here's an excellent tutorial on RPM. How do you intend to talk to this remote server? Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered.

Check to see if a directory exists remotely shell script Ask Question. Asked 10 years, 3 months ago. Active 6 years, 4 months ago.

Viewed 27k times. Is there a way to see if a directory exists on a remote server? Thanks in advance! Active Oldest Votes. Rory Rory This didn't work for me probably your backquotes got mangled.

Kim Kim 1 1 gold badge 5 5 silver badges 11 11 bronze badges. I added it, but it depends on what exactly he wants. Now he can't use the command in an if statement anymore. Chopper3 Chopper3 It can be accessed through SSH, however I wasn't sure if there is another tool that will allow me to create the directory. If you have SSH simply script an mkdir, if it exists it'll just fail with an error.Welcome to the most active Linux Forum on the web.

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For more advanced trainees it can be a desktop reference, and a collection of the base knowledge needed to proceed with system and network administration. This book contains many real life examples derived from the author's experience as a Linux system and network administrator, trainer and consultant.

They hope these examples will help you to get a better understanding of the Linux system and that you feel encouraged to try out things on your own. Click Here to receive this Complete Guide absolutely free. I am running this in a crontab file and I dont want any output telling me that the directory exists.

I just want to check if the directory doesnt exist, create one else do nothing not even a message telling me that the directory exists. Here is what I tried: 1.

Any suggestions? Try using double brackets: Code:. Your third try is the proper syntax. Try quoting your variable Code:. Last edited by sploot; at AM. Reason: fixed it. Use mkdir -p instead. It does not complain if directory already exists. Well color me confused??

Firstly I am curious why you would want to create a directory if one already existed or a file of the same name as implied by error message? Second, does this mean the test is inaccurate? I like this one most: Code:.There are several functions in Linux that only work if a particular file or directory exists.

Bash is a shell that interprets commands. You can use a bash command to check if a file or directory exists. Note: You may encounter the term bash script. This is a sequence of several commands to the shell. A script can be saved as a file and is often used to automate multiple system commands into a single action. The first line executes the test to see if the file exists. The second command, echodisplays the results 0 meaning that the file exists, 1 means no file was found.

To c heck if a directory exists, s witch out the —f option on the test command for —d for directory :. This command works the same as it does for files, so using brackets instead of the test command works here also. Note: If you are searching for a file or directory because you need to delete it, refer to our guide on removing files and directories with Linux command line.

Typically, testing for a file returns 0 true if the file exists, and 1 false if the file does not exist.

bash if directory exists

For some operations, you may want to reverse the logic. The exclamation point! This command makes sure there is not a file named test.

bash if directory exists

You should see test. You can use a similar command for a directory — replace the —f option with —d :. As usual, changing the —f option to —d lets you run the same test for multiple directories.

The previous commands work well for a simple two-line command at a command prompt. You can also use bash with multiple commands.If you are working on a Bash script that interacts with files and directories, you might encounter a situation where you need to make sure that the file or directory exists. The idea here is to use the -f operator that returns true only when it is a regular file not directory.

Basically, what matters is the condition you use in the if command. You can also use test in bash to see if file exists or not. You can use pretty much the same code as above by using the negation operator:.

The code for checking directory is the same as the one you saw in the previous section. I hope you find this bash tip useful. If you have any questions or suggestions, please feel free to leave a comment below. Liked the article? Please share it and help us grow :. Helping people with Linux is my ultimate goal.

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Please share it and help us grow : 5 Shares. Close dialog.Bash if statements are very useful. In this section of our Bash Scripting Tutorial you will learn the ways you may use if statements in your Bash scripts to help automate tasks. If statements and, closely related, case statements allow us to make decisions in our Bash scripts. They allow us to decide whether or not to run a piece of code based upon conditions that we may set.

If statements, combined with loops which we'll look at in the next section allow us to make much more complex scripts which may solve larger tasks. Like what we have looked at in previous sections, their syntax is very specific so stay on top of all the little details.

A basic if statement effectively says, if a particular test is true, then perform a given set of actions.

How To Check If File or Directory Exists in Bash

If it is not true then don't perform those actions. If follows the format below:. Anything between then and fi if backwards will be executed only if the test between the square brackets is true. It is always good practice to test your scripts with input that covers the different scenarios that are possible. The square brackets [ ] in the if statement above are actually a reference to the command test.

Check if a directory exists in Linux or Unix shell

This means that all of the operators that test allows may be used here as well. Look up the man page for test to see all of the possible operators there are quite a few but some of the more common ones are listed below. You'll notice that in the if statement above we indented the commands that were run if the statement was true. This is referred to as indenting and is an important part of writing good, clean code in any language, not just Bash scripts.

The aim is to improve readability and make it harder for us to make simple, silly mistakes. There aren't any rules regarding indenting in Bash so you may indent or not indent however you like and your scripts will still run exactly the same. I would highly recommend you do indent your code however especially as your scripts get larger otherwise you will find it increasingly difficult to see the structure in your scripts.

Talking of indenting. Here's a perfect example of when it makes life easier for you. You may have as many if statements as necessary inside your script. It is also possible to have an if statement inside of another if statement. For example, we may want to analyse a number given on the command line like so:. Yo dawg, I herd you like if statements so I put an if statement inside your if statement.

Introduction to Bash Scripting 07 - Checking the Existence of Files and Folders

You can nest as many if statements as you like but as a general rule of thumb if you need to nest more than 3 levels deep you should probably have a think about reorganising your logic. Sometimes we want to perform a certain set of actions if a statement is true, and another set of actions if it is false.The following example takes an array of file or directory names on the command line, determines what kind of name it is, and processes it appropriately.

Check if a folder exists

The path parameter is permitted to specify relative or absolute path information. Relative path information is interpreted as relative to the current working directory. Trailing spaces are removed from the end of the path parameter before checking whether the directory exists.

If you do not have at a minimum read-only permission to the directory, the Exists method will return false. The Exists method returns false if any error occurs while trying to determine if the specified file exists. This can occur in situations that raise exceptions such as passing a file name with invalid characters or too many characters, a failing or missing disk, or if the caller does not have permission to read the file. Skip to main content. Exit focus mode.

IO Assemblies: mscorlib. Determines whether the given path refers to an existing directory on disk. Is this page helpful? Yes No. Any additional feedback? Skip Submit.