迺ｰ蠅�､画焚繧定ｨｭ螳壹☆繧�/setting environment variables ================================================ 繝励Ο繧ｰ繝ｩ繝�縺ｮ蜍穂ｽ懊ｒ繧ｫ繧ｹ繧ｿ繝槭う繧ｺ縺吶ｋ縺溘ａ縺ｫ縲√ヱ繝ｩ繝｡繧ｿ繧呈ｸ｡縺呎焔谿ｵ縺ｮ荳縺､縺ｫ 迺ｰ蠅�､画焚(environment variable)縺後≠繧翫∪縺吶よｼ皮ｿ堤ｧ醍岼縺ｮ荳ｭ縺ｧ菴募ｺｦ縺九∫腸蠅�､画焚縺ｫ 蛟､繧定ｨｭ螳壹☆繧句ｿ�ｦ√′逕溘§縺ｾ縺吶ゅ％縺ｮ繝√Η繝ｼ繝医Μ繧｢繝ｫ縺ｧ縺ｯ縺昴�險ｭ螳壹�莉墓婿繧堤ｴｹ莉九＠縺ｾ縺吶� 險ｭ螳壹�莉墓婿縺ｫ縺ｯ繝ｭ繧ｰ繧｢繧ｦ繝医☆繧九∪縺ｧ縺ｮ髢薙〒荳譎ら噪縺ｫ謖�ｮ壹☆繧区婿豕輔→縲� 繝輔ぃ繧､繝ｫ縺ｫ菫晏ｭ倥＠縺ｦ縺翫＞縺ｦ繝ｭ繧ｰ繧､繝ｳ縺ｮ蠎ｦ縺ｫ險ｭ螳壼､縺瑚ｪｭ縺ｿ霎ｼ縺ｾ繧後ｋ繧医≧縺ｫ 縺吶ｋ譁ｹ豕輔→縺後≠繧翫∪縺吶ゅ◎縺ｮ荳｡譁ｹ繧定ｪｬ譏弱＠縺ｾ縺吶�縺ｧ縲∝ｮ滄圀縺ｫ險ｭ螳壹＠縺ｦ縺翫＞縺ｦ縺上□縺輔＞縲� Environment variables is one way to give parameters to programs in order to customize their behavior. In the seminar, there will be several occasions that environment variables must be set. In this tutorial we will show how to do that. Environment variables can be set either temporary---i.e. set the value only until you logout, or permanently---i.e. store the value in a file so that the value will be used every time you log in. Both ways will be explained. Follow the instructions to actually do the setup. 迺ｰ蠅�､画焚縺ｨ縺ｯ菴輔°/What are environment variables ----------------------------------------------- 迺ｰ蠅�､画焚縺ｨ縺ｯ縲＾S縺� :term:`繝励Ο繧ｻ繧ｹ` 繧定ｵｷ蜍輔☆繧矩圀縺ｫ縲∬ｦｪ繝励Ο繧ｻ繧ｹ縺九ｉ蟄舌�繝ｭ繧ｻ繧ｹ縺ｫ 蠑輔″貂｡縺輔ｌ繧区枚蟄怜�蟆ら畑縺ｮ螟画焚縺ｧ縺吶� Environment variables are string-only variables that are passed from the parent process to the child process upon :term:`process` creation by the operating system. 蜈ｨ縺ｦ縺ｮ繝励Ο繧ｻ繧ｹ縺ｯ縲∬ｵｷ蜍墓凾縺ｫ隕ｪ繝励Ο繧ｻ繧ｹ縺九ｉ迺ｰ蠅�､画焚荳蠑上�繧ｳ繝斐�繧貞女縺醍ｶ吶℃縺ｾ縺吶� 荳闊ｬ逧�↑繝励Ο繧ｰ繝ｩ繝�縺ｧ縺ｯ迺ｰ蠅�､画焚縺ｮ蜀�ｮｹ縺ｯ隱ｭ縺ｿ蜃ｺ縺吶□縺代〒螟画峩縺ｯ縺励∪縺帙ｓ縲� 莉ｮ縺ｫ螟画峩縺励◆蝣ｴ蜷医√�繝ｭ繧ｻ繧ｹ縺ｫ荳弱∴繧峨ｌ縺溘さ繝斐�繧貞､画峩縺吶ｋ縺薙→縺ｫ縺ｪ繧九�縺ｧ縲� 隕ｪ繝励Ο繧ｻ繧ｹ縺ｮ迺ｰ蠅�､画焚縺ｯ螟峨ｏ繧翫∪縺帙ｓ縲� 螟画峩縺励◆蛟､縺ｯ縲∵峩縺ｫ蟄舌�繝ｭ繧ｻ繧ｹ繧定ｵｷ蜍輔＠縺溷�ｴ蜷医↓縲∝ｭ舌�繝ｭ繧ｻ繧ｹ縺ｫ蠑輔″邯吶′繧後∪縺吶� All newly born processes are given a copy of all the environment variables that were held by the parent process. Most programs will only read the values and will not modify. If a program modified an environment variable, it will be modifying the copy that was given to the process, so the value in the parent process will not be affected. If the process created child processes, the modified values will be passed to those child processes. 迺ｰ蠅�､画焚縺ｮ險ｭ螳壽焔谿ｵ/The means to set environemnt variables --------------------------------------------------------- 迺ｰ蠅�､画焚繧定ｨｭ螳壹☆繧倶ｸ闊ｬ逧�↑謇区ｮｵ縺ｯ縲� :term:`繧ｷ繧ｧ繝ｫ` 縺ｮ邨�∩霎ｼ縺ｿ 繧ｳ繝槭Φ繝峨〒險ｭ螳壹☆繧区婿豕輔〒縺吶０S縺ｫ繧医▲縺ｦ縺ｯ縲√％繧後↓蜉�縺医※OS迚ｹ譛峨� GUI縺ｫ繧医▲縺ｦ迺ｰ蠅�､画焚縺瑚ｨｭ螳壹〒縺阪ｋ繧医≧縺ｫ縺ｪ縺｣縺ｦ縺�ｋ縺薙→繧ゅ≠繧翫∪縺� (萓具ｼ啗indows縺ｮ繧ｳ繝ｳ繝医Ο繝ｼ繝ｫ繝代ロ繝ｫ)縲� The standard means to set environment variables is to use built-in commands of the :term:`shell`. Depending on the brand of OS, an additional GUI to set environment variables may be provided, for example, the control panel of Microsoft Windows. 迺ｰ蠅�､画焚縺ｮ蜀�ｮｹ繧堤｢ｺ隱阪☆繧�/Check the value of environment variables ----------------------------------------------------------------- 繧ｷ繧ｧ繝ｫ縺ｮ邨�∩霎ｼ縺ｿ繧ｳ繝槭Φ繝� echo 繧剃ｽｿ縺�→縲∫腸蠅�､画焚縺ｮ蜀�ｮｹ繧堤｢ｺ隱阪〒縺阪∪縺吶� 螟画焚縺ｮ蛟､繧貞盾辣ｧ縺吶ｋ縺ｫ縺ｯ縲∝､画焚蜷阪�蜑阪↓螟画焚蜿ら�貍皮ｮ怜ｭ� "$" 繧偵▽縺代∪縺吶� You can check the content of an environment variable with the builtin command 'echo'. To obtain the content of a variable, use the variable reference operator '$':: $ echo $SHELL /usr/bin/bash $ echo $USER hideo-t 螳夂ｾｩ縺輔ｌ縺ｦ縺�ｋ蜈ｨ縺ｦ縺ｮ迺ｰ蠅�､画焚繧定｡ｨ遉ｺ縺吶ｋ縺ｫ縺ｯ env 繧ｳ繝槭Φ繝峨ｒ菴ｿ縺�∪縺吶� To display all environment variables, use the env command:: $ env XDG_SEAT_PATH=/org/freedesktop/DisplayManager/Seat0 XDG_CONFIG_DIRS=/etc/xdg/xdg-xfce:/etc/xdg:/etc/xdg LANG=ja_JP.UTF-8 DISPLAY=:0.0 SHLVL=1 ... 荳譎ら噪縺ｫ迺ｰ蠅�､画焚繧定ｨｭ螳壹☆繧�/Setting environment variables temporarily -------------------------------------------------------------------- 繧ｷ繧ｧ繝ｫ縺ｮ螟画焚縺ｫ縺ｯ�育腸蠅�､画焚縺ｧ縺ｯ縺ｪ縺�ｼ峨す繧ｧ繝ｫ螟画焚縺ｨ迺ｰ蠅�､画焚縺後≠繧翫∪縺吶� shell縺ｮ遞ｮ鬘槭↓繧医▲縺ｦ縺ｯ繧ｷ繧ｧ繝ｫ螟画焚縺ｸ縺ｮ莉｣蜈･縺ｨ迺ｰ蠅�､画焚縺ｸ縺ｮ莉｣蜈･縺ｫ縲∝�縺� 逡ｰ縺ｪ繧区ｧ区枚繧剃ｽｿ縺�ｂ縺ｮ繧ゅ≠繧翫∪縺吶′縲｜ash,sh,zsh縺ｪ縺ｩ縺ｮ迴ｾ蝨ｨ蠎�￥菴ｿ繧上ｌ縺ｦ縺�ｋ 繧ｷ繧ｧ繝ｫ縺ｧ縺ｯ縲�Κ蛻�噪縺ｫ蜈ｱ騾壹�讒区枚繧剃ｽｿ縺�∪縺吶� 繧ｷ繧ｧ繝ｫ螟画焚縺ｫ荳譌ｦ莉｣蜈･縺励※縺九ｉ縲∫腸蠅�､画焚縺ｨ縺励※繧ｨ繧ｯ繧ｹ繝昴�繝医☆繧九� 縺ｨ縺�≧謇矩��〒迺ｰ蠅�､画焚縺ｫ險ｭ螳壹＠縺ｾ縺吶� Variables in shells come in two flavors, the (non-environment) shell variables, and environment variables. In some types of shell implementations the assignment to the two different variables take separate forms, but for the currently popular shells such as bash, sh, zsh, the two types of assignments take the same form up to a point. To assign a value to an environment variable, you first assign a value to a shell variable, then 'export' it to copy the value to an environemnt variable with the same name:: $ VAR_A="This is a shell var." $ VAR_B="This is an env var." $ export VAR_B $ echo $VAR_A This is a shell var. $ echo $VAR_B This is an env var. $ env | grep VAR_ VAR_B=This is an env var. $ bash $ echo $VAR_A $ echo $VAR_B This is an env var. $ exit echo $VAR_A This is a shell var. 荳翫�萓九〒縺ｯ騾比ｸｭ縺ｧbash繝励Ο繧ｰ繝ｩ繝�繧貞ｭ舌�繝ｭ繧ｻ繧ｹ縺ｨ縺励※襍ｷ蜍輔＠縺ｦ縺�∪縺吶� 隕ｪ縺ｮ繧ｷ繧ｧ繝ｫ縺九ｉ蟄舌�繝ｭ繧ｻ繧ｹ縺ｮ繧ｷ繧ｧ繝ｫ縺ｫ縺ｯ縲√す繧ｧ繝ｫ螟画焚縺ｯ蠑輔″邯吶′繧後↑縺��縺ｧ縲� 隕ｪ繝励Ο繧ｻ繧ｹ縺ｮ繧ｷ繧ｧ繝ｫ螟画焚 VAR_A 縺ｮ蜀�ｮｹ縺ｯ縲∝ｭ舌�繝ｭ繧ｻ繧ｹ縺ｧ縺ｯ譛ｪ螳夂ｾｩ縺ｫ縺ｪ縺｣縺ｦ縺�∪縺吶� In the above example, a bash program is invoked as a child process. Shell variables in the parent shell is not inherited to the latter shell running as the child process, therefore VAR_A, which is a shell variable of the parent process is undefined within the child process. 荳願ｨ倥�繧医≧縺ｫ險ｭ螳壹＆繧後◆迺ｰ蠅�､画焚縺ｯ繧ｷ繧ｧ繝ｫ縺ｮ繝｡繝｢繝ｪ縺ｮ荳ｭ縺ｫ縺励°蟄伜惠縺励↑縺��縺ｧ縲� 繧ｷ繧ｧ繝ｫ繧堤ｵゆｺ�☆繧九→豸医∴縺ｦ縺励∪縺�∪縺吶� 險ｭ螳壹ｒ繝輔ぃ繧､繝ｫ縺ｫ菫晏ｭ倥＠縺ｦ縲∵ｶ医∴縺ｪ縺�ｈ縺�↓縺吶ｋ譁ｹ豕輔ｒ谺｡縺ｫ邏ｹ莉九＠縺ｾ縺吶� Environment variables that were set in the above way exists only in memory, and will be lost when you exit from the shell. We will next see how the setting can be stored into a file so that it won't be lost. 繧ｷ繧ｧ繝ｫ縺ｮ蛻晄悄蛹悶ヵ繧｡繧､繝ｫ縺ｧ迺ｰ蠅�､画焚繧定ｨｭ螳壹☆繧区婿豕�/Setting environment variables in shell startup files --------------------------------------------------------------------------------------------------- bash縺ｮ蝣ｴ蜷医√�繝ｼ繝�繝�ぅ繝ｬ繧ｯ繝医Μ縺ｫ .profile 縺ｨ縺�≧繝輔ぃ繧､繝ｫ縺後≠繧後�縲� 譛蛻昴↓襍ｷ蜍輔☆繧九す繧ｧ繝ｫ縺後◎縺ｮ繝輔ぃ繧､繝ｫ繧定ｪｭ縺ｿ霎ｼ縺ｿ縺ｾ縺吶� 縺昴％縺ｫ迺ｰ蠅�､画焚縺ｸ縺ｮ莉｣蜈･繧呈嶌縺�※縺翫￠縺ｰ縲√Ο繧ｰ繧､繝ｳ縺ｮ蠎ｦ縺ｫ蜷後§蛟､縺瑚ｨｭ螳壹＆繧後ｋ 繧医≧縺ｫ縺ｪ繧翫∪縺吶� In the case of bash, if there is a file named .profile in your home directory, the first shell in your login session will read that file. By placing environment variable assignments in that file, the settings will be read every time you log in. 迺ｰ蠅�､画焚縺ｸ縺ｮ險ｭ螳壹′縺励�縺励�蠢�ｦ√↓縺ｪ繧倶ｾ九→縺励※縲∫腸蠅�､画焚 :term:`PATH` 縺ｫ 繝�ぅ繝ｬ繧ｯ繝医Μ蜷阪ｒ霑ｽ蜉�縺吶ｋ萓九ｒ遉ｺ縺励∪縺吶� .profile繧堤ｷｨ髮�☆繧九↓縺ｯ :ref:`繝�く繧ｹ繝医お繝�ぅ繧ｿ<text-editor>` 繧剃ｽｿ縺�∪縺吶� As an example of a common cause for setting environment variables, adding a directory to the directory list that is held by the environment variable :term:`PATH` can be done as follows. Use a :ref:`Text Editor<text-editor>` to edit the .profile file.:: MY_BIN_PATH=~/.local/bin INSTRUCTOR_BIN_PATH=~/bin PATH=$PATH:$MY_BIN_PATH:$INSTRUCTOR_BIN_PATH export PATH 荳願ｨ倥�萓九〒縺ｯ縲∬�蛻��繝帙�繝�繝�ぅ繝ｬ繧ｯ繝医Μ縺ｮ荳九↓縺ゅｋ .local/bin 繝�ぅ繝ｬ繧ｯ繝医Μ縺ｨ縲∵ｼ皮ｿ堤ｧ醍岼縺ｮ隰帛ｸｫ縺ｮ繝帙�繝�繝�ぅ繝ｬ繧ｯ繝医Μ縺ｮ荳九↓縺ゅｋ pub/bin繝�ぅ繝ｬ繧ｯ繝医Μ縺訓ATH縺ｫ霑ｽ蜉�縺輔ｌ縺ｾ縺吶� The above example will add two directories to your path; a .local/bin directory under your home directory, and a pub/bin directory under the instructor's home directory. .profile縺ｫPATH縺ｮ險ｭ螳壹ｒ霑ｽ蜉�縺励◆逶ｴ蠕後�縲√∪縺�繝輔ぃ繧､繝ｫ縺後す繧ｧ繝ｫ縺ｫ 隱ｭ縺ｿ霎ｼ縺ｾ繧後※縺�↑縺��縺ｧ險ｭ螳壼�螳ｹ縺悟渚譏�縺輔ｌ縺ｪ縺�％縺ｨ縺ｫ豕ｨ諢上＠縺ｦ縺上□縺輔＞縲� 荳蠎ｦ繝ｭ繧ｰ繧｢繧ｦ繝医＠縺ｦ繝ｭ繧ｰ繧､繝ｳ縺励↑縺翫☆縺ｨ縲∝渚譏�縺輔ｌ縺ｾ縺吶� 縺薙�繝輔ぃ繧､繝ｫ縺ｮ譖ｸ縺肴婿縺ｯ縲∝ｽ灘�縺ｧ縺ｪ縺�％縺ｨ縺ｫ豕ｨ諢上＠縺ｦ縺上□縺輔＞縲� 迺ｰ蠅�､画焚PATH縺ｫ縺ｯ蜈�°繧牙､縺瑚ｨｭ螳壹＆繧後※縺翫ｊ縲√◎繧後↓霑ｽ蜉�縺吶ｋ繧医≧縺ｫ 譖ｸ縺�※縺�∪縺吶ゆｽ輔ｉ縺九�逅�罰縺ｧ.profile繧定､�焚蝗槫ｮ溯｡後☆繧九→縲� 霑ｽ蜉�蜃ｦ逅�′菴募ｺｦ繧り｡後ｏ繧後※縺励∪縺�∪縺吶ゅ◎繧後ｒ髦ｲ縺先婿豕輔ｂ縺ゅｊ縺ｾ縺吶�縺ｧ 闊亥袖縺ｮ貉ｧ縺�◆譁ｹ縺ｯ縲∬ｪｿ縺ｹ縺ｦ縺ｿ縺ｦ縺上□縺輔＞縲� Note that the PATH assignment that has been added to your .profile file will not be reflected immediately to an already running shell. The assignment will take effect once you log out and log in again. Also note that the way the file is written is not idempotent. The environment variable PATH will already have some value set, and the above code will append a string to the existing value. If, for some reason, .profile is read and executed multiple times, the appending operation will be run multiple times. There are ways to avoid that. If you are interested, try some searching.