Linux change temp directory

Linux tmp Directory: Everything You Need to Know

If you are coming from the Windows environment, the chances are that you may think the tmp directory is something safe to delete. That’s not the case! Unless you know what you are doing, we don’t want advice to remove anything in the tmp directory. Here is everything you need to know. Read on.

A re you looking to expand your knowledge base on how temporary files are handled in Linux? Well, to help you out, here is a quick and comprehensive read on everything you need to know about the Linux /tmp directory.

What is the Linux /tmp Directory?

The /tmp directory in Linux based systems contains necessary files that are temporarily required by the system as well as other software and applications running on the machine.

tmp directory on Pop!_OS (example)

For example, when you are writing a document, all the content inside that document is saved as a temporary file inside the /tmp directory. After you have saved it, it gets stored in your preferred location, and the temporary file gets removed once you exit the document.

What is the difference between the /tmp directory and the /var/tmp Directory?

Both /tmp and /var/tmp are used by programs as well as the system itself to store data temporarily. However, the key difference is for how long the data is stored inside these filesystems. The data retention period for /var/tmp is much more extended than that of the /tmp directory.

By default, all the files and data that gets stored in /var/tmp live for up to 30 days. Whereas in /tmp, the data gets automatically deleted after ten days.

Furthermore, any temporary files that are stored in the /tmp directory get removed immediately on system reboot. As such, the /var/tmp directory is used by programs to store data that needs to be preserved between reboots temporarily.

Can the Linux /tmp directory fill up?

The files and data that are stored inside the /tmp directory are only a few KB in size. It is doubtful, albeit possible, for the /tmp directory to fill up.

For an average system, there needs to be millions of temporary files stored in the /tmp directory to fill it up. This shouldn’t be something you should worry about if you run a single-user system that gets frequently shut down, as the rebooting system removes all the stored files in the /tmp directory.

However, if you are a system admin running a server that rarely gets rebooted and hosts thousands of users, then the /tmp directory filling up is a practical problem.

With more temporary files piling up in the directory, it is going to slowly eat up all the storage space, which is terrible news for the overall system health.

How to delete the files stored inside the /tmp directory?

Unless you know what you are doing, it isn’t recommended that you go around deleting the files inside the /tmp directory. These are important and required by the software running on your system. Removing them can potentially cause a system crash. Since the files and data stored in the /tmp directory get automatically deleted upon system reboot, it isn’t something you need to worry about actively.

However, as discussed earlier, for servers that run for months on end, it is necessary to clean up the temporary files from time to time before it floods the /tmp directory. To do this, we encourage you to take a more systematic approach instead of just deleting all the /tmp files by the bunch.

Here we have put together a detailed read on how to properly manage the Linux /tmp directory to help out system admins.

The correct way to delete Temporary Files and Manage the Linux /tmp directory

There are two things you need to consider when trying to manage the Linux /tmp directory. First, you need to know how to determine which files to remove from the /tmp directory, as randomly deleting the files will disrupt users’ activities.

Secondly, you need a way to automate the /tmp directory clean up process as it is going to be impossible to search and routinely delete the temporary files manually.

Considering these two points, the perfect solution would be periodically deploying user file housekeeping scripts using crontab. For example, let’s suppose that you want to routinely delete all user files stored in the /tmp directory that has not been used for the last three days.

Well, you can put this to action by first informing the users on your server about your new temporary file deletion policy, so that they can modify their usage activities accordingly. Next, you will need to write a script that will help you find all these files.

Here is an example that you can try:

The above script will find all the /tmp files that haven’t been accessed in the last three days but will exclude all the files owned by the root user. To delete all these files, you will just to do a slight edit to the above script:

To run this script periodically, you will need to copy the above text in a file and make it executable. For this tutorial, we will be creating the file tmp.cleanup.sh.

Script for deleting /tmp files

Next, we will set up a crontab command that will execute the script every 6 hours. To do this, first enter the following command in the terminal:

This is going to open the crontab file in the editor. Next, you will need to copy and paste the given command in the editor and then save & exit.

Creating a /tmp file deletion crontab

This is going to run the script in /opt/scripts/tmp.cleanup.sh, every 6 hours, so you don’t have to worry about the /tmp directory getting flooded and eating up your system storage.

Of course, you are free to program the crontab to execute the script in any periodic interval you want. Here is an in-depth guide on how to create a crontab command to help you out.

I accidentally deleted the /tmp directory. Now what?

In the course of manually deleting the /tmp files, some users accidentally end up deleting the /tmp directory itself. Mess ups like this can and do happen. However, you can quickly restore the deleted /tmp directory using the discussed method.

All you need to do is enter the following commands in your terminal:

The first line creates a new /tmp directory. The second line gives all users (owner, group, and other) access and permission to read, write, and run files in the /tmp directory.

Next, you can enter this command to check all the permissions of the /tmp directory to make sure all your users will be able to use it.

Once you have checked everything is a-okay, you will need to reboot your system. This will ensure that the programs start using the newly created /tmp directory.

Wrapping Up

So that covers everything you need to know about the Linux /tmp directory. However, if you still have some burning questions that we left out from this read, then feel free to ask them down in the comments section. We will happily resolve it to help you develop a better understanding and appreciation for Linux.

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Где временный каталог в Linux?

Есть ли в Linux стандартный временный каталог для общего пользования, например, C:\Temp папка Windows ? Если да, где он находится? Я нашел SO вопрос о программном поиске tmp каталога , но я хочу заранее установить временное местоположение в XML-файле конфигурации.

/ tmp: временные файлы

/tmp Каталог должен быть доступен для программ , которые требуют временных файлов.

Программы не должны предполагать, что какие-либо файлы или каталоги в /tmp них сохраняются между вызовами программы.

обоснование

Стандарт IEEE POSIX.1-2008 перечисляет требования, аналогичные приведенному выше разделу. Хотя данные, хранящиеся в, /tmp могут быть удалены в зависимости от сайта, рекомендуется, чтобы файлы и каталоги, расположенные в /tmp них, удалялись при каждой загрузке системы.

FHS добавил эту рекомендацию на основе исторического прецедента и общепринятой практики, но не сделал ее обязательным требованием, поскольку системное администрирование не входит в сферу применения этого стандарта.

/ var / tmp: временные файлы сохраняются между перезагрузками системы

/var/tmp Каталог доступен для программ , которым требуется временные файлы или каталоги , которые должны сохраняться между перезагрузками системы. Поэтому данные, хранящиеся в, /var/tmp являются более постоянными, чем данные в /tmp .

Файлы и каталоги, расположенные в, /var/tmp не должны быть удалены при загрузке системы. Несмотря на то, что данные, хранящиеся в, /var/tmp как правило, удаляются в зависимости от сайта, рекомендуется, чтобы удаление происходило с меньшей частотой, чем /tmp .

TMPDIR Эта переменная должна представлять путь к каталогу, доступному для программ, которым требуется место для создания временных файлов.

Это старый вопрос, поэтому сегодня есть еще один вариант. Дистрибутивы Linux, на systemd которые полагается (а это 90%), теперь могут использовать $XDG_RUNTIME_DIR каталог ( спецификация XDG Base Directory ) для хранения определенных типов временных файлов. Обычно он находится по адресу /run/user/$uid . Это каталог для пользователя с 700 разрешениями, которые обеспечивают лучшую безопасность. Это tmpfs крепление, которое обеспечивает производительность. Недостатком tmpfs является то, что он должен использоваться только для хранения небольших файлов и сокетов.

Я смотрю на это как на брак /tmp и /var/run .

Да / TMP для общего пользования. Смотрите здесь и здесь О стандарте иерархии файловой системы.

/ tmp / Временные файлы (см. также / var / tmp). Часто не сохраняется между перезагрузками системы.

С некоторыми подробностями, перечисленными в PDF.

Вы не можете заранее выбрать одно временное имя каталога, которое будет работать для любой системы Linux. На самом деле, вы не можете сделать это и в Windows. Согласно статье Википедии о временных папках , временный каталог в Windows определяется переменной среды TEMP. Если бы вы просто использовали c:\Temp в качестве временного каталога в системе Windows, в котором для TEMP установлено другое значение, любая программа, использующая ваш XML-файл для выбора временного каталога, потерпит неудачу.

Короче говоря, системный временный каталог определяется средой во всех известных мне современных операционных системах, включая как Windows, так и любую UNIX-подобную систему. Установка одного статического пути в качестве временного каталога будет работать только до тех пор, пока значения по умолчанию не будут изменены.

Во всяком случае, стандартный временный каталог в типичной системе Linux есть /tmp . Это эквивалент C:\Temp в том смысле, что это только временный каталог по умолчанию, а не универсальный. Даже если /tmp доступно, если пользователь (или система) установил переменную среды TEMP, вместо нее следует использовать значение этой переменной.

Вы можете попробовать выбрать временный каталог относительно домашнего каталога пользователя, который вы можете создать.

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Create temporary directory on Linux with Bash using mktemp

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When writing a test or whenn running a build job it is usually a good practice to use a temporary directory and then clean up after the process is done.

It is also a good practice to make sure the temporary directoy is unique so if two processes run at the same time they won’t interfere.

In Linux one usually has a directory called /tmp to store temporary files. In most of the programming languages there is some tool to create temporary directories. Sometimes these also handle the removal of these directories once they are not needed any more.

In Unix/Linux shell we can use the mktemp commmand to create a temporary directory inside the /tmp directory.

The -d flag instructs the command to create the directory.

The -t flag allows us to provide a template. Each X character will be replaced by a random character. The more such characters the better your chances of having a unique directory. The rest of the template can and should be use to make it clear what is the purpose of the directory. In the above example this directory was created for and by the CI system.

The command will print the directory to the screen, but you can capture it to a variable and you can use it to create your files in this temporary directory.

At the end of the process you will probably want to remove the directory.

Here is a full example:

It will print the name of the directory that will look like this:

Date based directory

It can be also a good idea to include the date in the name of the directory. Especially if we might keep it for later observation. In any case here is an example on how to generate a temporary directory that has a fixed part, a date-based part, and a random part:

The directory name will look like this:

Other root directory

By default the temporary directory will be created inside the /tmp directory. Sometimes we might want it to be in some other directory. For example I’ve created a tmp directory in my home directory and wanted to place the temporary directories inside that directory:

The path to the new directory will look like this:

For further options you might want to check out the documentation of mktemp.

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How to change directory in Linux terminal

M y Dell Laptop came preinstalled with Ubuntu Linux, and I am a new Linux desktop user. How do I change directories in the Linux terminal?

Introduction – On Linux the cd command allows you to change directories when using the terminal application. This page shows how to change directory in Linux terminal using the cd command.

Tutorial details
Difficulty level	Easy
Root privileges	No
Requirements	Linux terminal
Est. reading time	3 minutes

How to change directory in Linux terminal

1. To return to the home directory immediately, use cd

OR cd

To change into the root directory of Linux file system, use cd / .

To go into the root user directory, run cd /root/ as root user.

To navigate up one directory level up, use cd ..

To go back to the previous directory, use cd —

Let us see all examples and usage for terminal in details.

How to use the Linux command line to change directory or folder

The directory in which the user is currently working is called the current working directory (CDW).

How to print the current working directory in Linux

To display the name of the current/working directory, type the following pwd command:
pwd

cd command in Linux termianl

The syntax is:
cd
cd ..
cd /path/to/dir
When cd command used without stipulating any directory name, cd command returns to the home directory. Let us change the directory to /usr/sbin/, run:
cd /usr/sbin/
Verify it:
pwd
Want to list the files in the /usb/sbin/ directory? Try the ls command:
ls
ls -l
Let us go back to user’s home directory, run:
cd
Again verify it:
pwd

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Absolute vs Relative pathname

The cd command changes the current directory when a directory name provided by the user. The name can be written as an absolute pathname (e.g. cd /etc/httpd/ ) or as local pathname relative to the root directory (e.g. cd conf.d/ ). For example:
cd /etc/httpd/
pwd
ls
cd conf.d/
pwd
ls

The absolute vs. relative pathname for cd command in Linux

Understanding . and .. directories

On Linux the current directory is represented by a single dot ( . ) and two consecutive dots represent its parent directory ( .. ). Thus, to change to the parent of the current directory, run cd . .. For example:
ls
pwd
cd ..
pwd
ls

How can I return directly to my home directory when using the Linux terminal?

How do I change directories in the Linux terminal and return to the previous directory?

Simply pass the — option to the cd:
cd —
Verify it:
pwd

A note about symbolic links and cd command

The -P option instructs cd to use the physical directory structure instead of following symbolic links:
cd -P LinkDir
pwd
The -L option forces cd to follow symbolic links:
cd -L LinkDir
pwd

Linux cd command cheat sheet

Table 1: cd command under Linux

Command	Description
cd	Returns you to your login directory
cd

Also returns you to your login directory cd — Returns you to your previous working directory cd / Takes you to the entire system’s root directory. cd /root Takes you to the home directory of the root user. You must be the root user to access this directory. cd /home Takes you to the home directory, where user login directories are usually stored cd .. Takes you to the directory one level up. cd

tom Takes you to tom’s home directory, if tom user has granted you permission cd /path/to/dir/ Take you to the /path/to/dir/ directory cd dir* Use a wildcard to change the directory name

Conclusion

The cd command is used to change the current directory in both Linux and other Unix-like systems. See Cd command wiki page.

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