Linux add command to path

How to add directory to system path in Linux

In Linux, the PATH environment variable stores the names of paths that will be searched for the executable files of any commands typed in the command line. The value of the PATH environment variable is a string containing a series of pathnames, each delimited by a colon. For instance, the default PATH on a typical system might look like this:

When you type a command such as cat and press Enter , the shell searches each of these directories for an executable file named cat. The first one it finds is the one it runs.

To view the current value of your PATH environment variable, you can use the echo command. As with all variables in the shell, when referring to the value you need to put a dollar sign before the variable name:

In the above example, the current value of path return you to the command prompt.

Setting PATH for your current shell session

You can set the value of PATH as you would any other shell variable, with the form NAME=VALUE, like this:

The problem with this command is that it will completely overwrite the values you had before, which you probably don’t want. If you want to add a new value in addition to the old ones. You can accomplish this by referring to PATH in the new definition, like this:

Using the command above adds your new path to the current value of PATH. Since the pathnames are searched in order, you probably want to add your new path at the end of the variable as we’ve done here. Instead, if you typed:

Your new path would be searched before, not after, the default system paths.

Using export to pass the PATH environment variable to child processes

This type of PATH definition sets the environment variable for your current shell session, but any new programs you run might not see the new path you’ve added. That’s because your shell lets you control the environment by requiring you to manually declare what environment variables are passed on to other programs and processes. You can accomplished this with the export command. If you run:

Any processes you run until you log out use the current value of PATH.

If you prefer, you can combine these two commands into a single line, for convenience. Put a semicolon between them so that the shell knows they’re separate commands:

If any of your pathnames have spaces in them, enclose the variable definition in quotation marks, to be safe.

Setting the PATH variable for every new shell session

The methods we’ve used so far only sets the environment variable for your current shell session; when you logout or close the terminal window, your changes will be forgotten. If you want to set PATH to a certain value every time you log in or start a new shell session, add it to your bash startup script. Every time you start an interactive shell session, bash reads the following files in order (if they exist), and executes the commands inside of them:

The first file, /etc/profile, is the default startup script for every user on the system. One or more of the remaining three files are located in the home directory of every user. Any of those three can be used, but it’s important to know that they will be searched for in this order.

You can edit these files and manually change any lines containing PATH= definitions. Be careful if you do so, because these are the directories used to locate important operating system files.

If you want to add a path for your current user only, you can leave the other PATH= lines untouched. Add a line like this to the end of the file:

If you add this to the end of the .bash_profile file in your home directory, it takes effect every time your user starts a new shell session. If you add this to /etc/profile, it takes effect for every user on the system. Note that you need administrator privileges if you want to edit /etc/profile, so you can use sudo (or be logged in as root) to do so.

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Переменная PATH в Linux

Когда вы запускаете программу из терминала или скрипта, то обычно пишете только имя файла программы. Однако, ОС Linux спроектирована так, что исполняемые и связанные с ними файлы программ распределяются по различным специализированным каталогам. Например, библиотеки устанавливаются в /lib или /usr/lib, конфигурационные файлы в /etc, а исполняемые файлы в /sbin/, /usr/bin или /bin.

Таких местоположений несколько. Откуда операционная система знает где искать требуемую программу или её компонент? Всё просто — для этого используется переменная PATH. Эта переменная позволяет существенно сократить длину набираемых команд в терминале или в скрипте, освобождая от необходимости каждый раз указывать полные пути к требуемым файлам. В этой статье мы разберёмся зачем нужна переменная PATH Linux, а также как добавить к её значению имена своих пользовательских каталогов.

Переменная PATH в Linux

Для того, чтобы посмотреть содержимое переменной PATH в Linux, выполните в терминале команду:

На экране появится перечень папок, разделённых двоеточием. Алгоритм поиска пути к требуемой программе при её запуске довольно прост. Сначала ОС ищет исполняемый файл с заданным именем в текущей папке. Если находит, запускает на выполнение, если нет, проверяет каталоги, перечисленные в переменной PATH, в установленном там порядке. Таким образом, добавив свои папки к содержимому этой переменной, вы добавляете новые места размещения исполняемых и связанных с ними файлов.

Для того, чтобы добавить новый путь к переменной PATH, можно воспользоваться командой export. Например, давайте добавим к значению переменной PATH папку/opt/local/bin. Для того, чтобы не перезаписать имеющееся значение переменной PATH новым, нужно именно добавить (дописать) это новое значение к уже имеющемуся, не забыв о разделителе-двоеточии:

Теперь мы можем убедиться, что в переменной PATH содержится также и имя этой, добавленной нами, папки:

Вы уже знаете как в Linux добавить имя требуемой папки в переменную PATH, но есть одна проблема — после перезагрузки компьютера или открытия нового сеанса терминала все изменения пропадут, ваша переменная PATH будет иметь то же значение, что и раньше. Для того, чтобы этого не произошло, нужно закрепить новое текущее значение переменной PATH в конфигурационном системном файле.

В ОС Ubuntu значение переменной PATH содержится в файле /etc/environment, в некоторых других дистрибутивах её также можно найти и в файле /etc/profile. Вы можете открыть файл /etc/environment и вручную дописать туда нужное значение:

sudo vi /etc/environment

Можно поступить и иначе. Содержимое файла .bashrc выполняется при каждом запуске оболочки Bash. Если добавить в конец файла команду export, то для каждой загружаемой оболочки будет автоматически выполняться добавление имени требуемой папки в переменную PATH, но только для текущего пользователя:

Выводы

В этой статье мы рассмотрели вопрос о том, зачем нужна переменная окружения PATH в Linux и как добавлять к её значению новые пути поиска исполняемых и связанных с ними файлов. Как видите, всё делается достаточно просто. Таким образом вы можете добавить столько папок для поиска и хранения исполняемых файлов, сколько вам требуется.

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Add a bash script to path

I want to add a small script to the linux PATH so I don’t have to actually run it where it’s physically placed on disk.

The script is quite simple is about giving apt-get access through a proxy I made it like this:

Then I saved this as apt-proxy.sh, set it to +x (chmod) and everything is working fine when I am in the directory where this file is placed.

My question is : how to add this apt-proxy to PATH so I can actually call it as if it where the real apt-get ? [from anywhere]

Looking for command line only solutions, if you know how to do by GUI its nice, but not what I am looking for.

4 Answers 4

Save the script as apt-proxy (without the .sh extension) in some directory, like

/bin to your PATH , typing export PATH=$PATH:

/bin
If you need it permanently, add that last line in your

/.bashrc . If you’re using zsh , then add it to

/.zshrc instead.

Then you can just run apt-proxy with your arguments and it will run anywhere.

Note that if you export the PATH variable in a specific window it won’t update in other bash instances.

properly. you may use absolute path or $HOME instead.

You want to define that directory to the path variable, not the actual binary e.g.

where MYDIR is defined as the directory containing your binary e.g.

You should put this in your startup script e.g. .bashrc such that it runs each time a shell process is invoked.

Note that order is important, and the PATH is evaluated such that if a script matching your name is found in an earlier entry in the path variable, then that’s the one you’ll execute. So you could name your script as apt-get and put it earlier in the path. I wouldn’t do that since it’s confusing. You may want to investigate shell aliases instead.

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How to correctly add a path to PATH?

I’m wondering where a new path has to be added to the PATH environment variable. I know this can be accomplished by editing .bashrc (for example), but it’s not clear how to do this.

12 Answers 12

The simple stuff

depending on whether you want to add

/opt/bin at the end (to be searched after all other directories, in case there is a program by the same name in multiple directories) or at the beginning (to be searched before all other directories).

You can add multiple entries at the same time. PATH=$PATH:

/opt/node/bin or variations on the ordering work just fine. Don’t put export at the beginning of the line as it has additional complications (see below under “Notes on shells other than bash”).

If your PATH gets built by many different components, you might end up with duplicate entries. See How to add home directory path to be discovered by Unix which command? and Remove duplicate $PATH entries with awk command to avoid adding duplicates or remove them.

Some distributions automatically put

/bin in your PATH if it exists, by the way.

Where to put it

Put the line to modify PATH in

/.bash_profile if that’s what you have.

/.bash_rc is not read by any program, and

/.bashrc is the configuration file of interactive instances of bash. You should not define environment variables in

/.bashrc . The right place to define environment variables such as PATH is

/.bash_profile if you don’t care about shells other than bash). See What’s the difference between them and which one should I use?

Don’t put it in /etc/environment or

/.pam_environment : these are not shell files, you can’t use substitutions like $PATH in there. In these files, you can only override a variable, not add to it.

Potential complications in some system scripts

You don’t need export if the variable is already in the environment: any change of the value of the variable is reflected in the environment.¹ PATH is pretty much always in the environment; all unix systems set it very early on (usually in the very first process, in fact).

At login time, you can rely on PATH being already in the environment, and already containing some system directories. If you’re writing a script that may be executed early while setting up some kind of virtual environment, you may need to ensure that PATH is non-empty and exported: if PATH is still unset, then something like PATH=$PATH:/some/directory would set PATH to :/some/directory , and the empty component at the beginning means the current directory (like .:/some/directory ).

Notes on shells other than bash

In bash, ksh and zsh, export is special syntax, and both PATH=

/opt/bin:$PATH and export PATH=

/opt/bin:$PATH do the right thing even. In other Bourne/POSIX-style shells such as dash (which is /bin/sh on many systems), export is parsed as an ordinary command, which implies two differences:

is only parsed at the beginning of a word, except in assignments (see How to add home directory path to be discovered by Unix which command? for details);

$PATH outside double quotes breaks if PATH contains whitespace or \[*? .

So in shells like dash, export PATH=

/opt/bin:$PATH sets PATH to the literal string

/opt/bin/: followed by the value of PATH up to the first space. PATH=

/opt/bin:$PATH (a bare assignment) doesn’t require quotes and does the right thing. If you want to use export in a portable script, you need to write export PATH=»$HOME/opt/bin:$PATH» , or PATH=

/opt/bin:$PATH; export PATH (or PATH=$HOME/opt/bin:$PATH; export PATH for portability to even the Bourne shell that didn’t accept export var=value and didn’t do tilde expansion).

¹ _{This wasn’t true in Bourne shells (as in the actual Bourne shell, not modern POSIX-style shells), but you’re highly unlikely to encounter such old shells these days.}

/.bashrc«, but unfortunately 100% of the programs that I have installed on my system that modify the path (FZF and Rust’s Cargo) modify the path in .bashrc . I assume because FZF is written in Rust too it’s following the pattern of Rust.

Either way works, but they don’t do the same thing: the elements of PATH are checked left to right. In your first example, executables in

/opt/bin will have precedence over those installed, for example, in /usr/bin , which may or may not be what you want.

In particular, from a safety point of view, it is dangerous to add paths to the front, because if someone can gain write access to your

/opt/bin , they can put, for example, a different ls in there, which you’d then probably use instead of /bin/ls without noticing. Now imagine the same for ssh or your browser or choice. (The same goes triply for putting . in your path.)

The bullet-proof way of Appending/Prepending

Try not using

Why? There are a lot of considerations involved in the choice of appending versus prepending. Many of them are covered in other answers, so I will not repeat them here.

An important point is that, even if system scripts do not use this (I wonder why) *1 , the bullet-proof way to add a path (e.g.,

/opt/bin ) to the PATH environment variable is

for appending (instead of PATH=»$PATH:

for prepending (instead of PATH=»

This avoids the spurious leading/trailing colon when $PATH is initially empty, which can have undesired side effects and can become a nightmare, elusive to find (this answer briefly deals with the case the awk -way).

If parameter is null or unset, nothing is substituted, otherwise the expansion of word is substituted.

1. nothing, if PATH is null or unset,
2. $: , if PATH is set.

Note: This is for bash.

*1 I have just found that scripts like `devtoolset-6/enable` actually use this,

I’m confused by question 2 (since removed from the question since it was due to an unrelated issue):

What’s a workable way to append more paths on different lines? Initially I thought this could do the trick:

but it doesn’t because the second assignment doesn’t only append

/opt/node/bin , but also the whole PATH previously assigned.

This is a possible workaround:

but for readability I’d prefer to have one assignment for one path.

that’s all that will be in your PATH. PATH is just an environment variable, and if you want to add to the PATH, you have to rebuild the variable with exactly the contents you want. That is, what you give as an example to question 2 is exactly what you want to do, unless I’m totally missing the point of the question.

I use both forms in my code. I have a generic profile that I install on every machine I work on that looks like this, to accommodate for potentially-missing directories:

Linux determines the executable search path with the $PATH environment variable. To add directory /data/myscripts to the beginning of the $PATH environment variable, use the following:

To add that directory to the end of the path, use the following command:

But the preceding are not sufficient because when you set an environment variable inside a script, that change is effective only within the script. There are only two ways around this limitation:

• If within the script, you export the environment variable it is effective within any programs called by the script. Note that it is not effective within the program that called the script.
• If the program that calls the script does so by inclusion instead of calling, any environment changes in the script are effective within the calling program. Such inclusion can be done with the dot command or the source command.

Inclusion basically incorporates the «called» script in the «calling» script. It’s like a #include in C. So it’s effective inside the «calling» script or program. But of course, it’s not effective in any programs or scripts called by the calling program. To make it effective all the way down the call chain, you must follow the setting of the environment variable with an export command.

As an example, the bash shell program incorporates the contents of file .bash_profile by inclusion. Place the following 2 lines in .bash_profile:

effectively puts those 2 lines of code in the bash program. So within bash, the $PATH variable includes $HOME/myscript.sh , and because of the export statement, any programs called by bash have the altered $PATH variable. And because any programs you run from a bash prompt are called by bash, the new path is in force for anything you run from the bash prompt.

The bottom line is that to add a new directory to the path, you must append or prepend the directory to the $PATH environment variable within a script included in the shell, and you must export the $PATH environment variable.

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