ubuntu 環境變數配置 並立即生效

Ubuntu Linux系統包含兩類環境變數：系統環境變數和使用者環境變數。系統環境變數對所有系統使用者都有效，使用者環境變數僅僅對當前的使用者有效。

環境變數

使用者環境變數通常被儲存在下面的檔案中：

    ~/.profile

    ~/.bash_profile 或者 ~./bash_login

    ~/.bashrc


系統環境變數

系統環境變數一般儲存在下面的檔案中：

    /etc/environment

    /etc/profile

    /etc/bash.bashrc

/etc/profile和 /etc/bash.bashrc在Ubuntu 10.0版本中不推薦使用。

加入環境變數

如想將一個路徑加入到$PATH中，可以像下面這樣做（修改使用者環境變數 .bashrc）：

    
終端執行$ gedit ~/.bashrc

在裡面加入:
#set android sdk
export SDK_ROOT=/home/jianjie/Android/adt-bundle-linux-x86-20131030/sdk
export PATH=$PATH:$SDK_ROOT/tools:$SDK_ROOT/platform-tools

#set android ndk
export NDK_ROOT=/home/jianjie/Android/android-ndk-r9b
export PATH=$PATH:$NDK_ROOT

#set eclipse
export ECLIPSE=/home/jianjie/Android/adt-bundle-linux-x86-20131030/eclipse
export PATH=$PATH:$ECLIPSE

你可以自己加上指定的多個路徑，中間用冒號隔開。環境變數更改後，在使用者下次登陸時生效，

如果想立刻生效，則可執行下面的語句：   

終端執行 $source ~/.bashrc

我的.bashrc檔案如下：

# ~/.bashrc: executed by bash(1) for non-login shells.
# see /usr/share/doc/bash/examples/startup-files (in the package bash-doc)
# for examples

# If not running interactively, don't do anything
[ -z "$PS1" ] && return

# don't put duplicate lines or lines starting with space in the history.
# See bash(1) for more options
HISTCONTROL=ignoreboth

# append to the history file, don't overwrite it
shopt -s histappend

# for setting history length see HISTSIZE and HISTFILESIZE in bash(1)
HISTSIZE=1000
HISTFILESIZE=2000

# check the window size after each command and, if necessary,
# update the values of LINES and COLUMNS.
shopt -s checkwinsize

# If set, the pattern "**" used in a pathname expansion context will
# match all files and zero or more directories and subdirectories.
#shopt -s globstar

# make less more friendly for non-text input files, see lesspipe(1)
[ -x /usr/bin/lesspipe ] && eval "$(SHELL=/bin/sh lesspipe)"

# set variable identifying the chroot you work in (used in the prompt below)
if [ -z "$debian_chroot" ] && [ -r /etc/debian_chroot ]; then
    debian_chroot=$(cat /etc/debian_chroot)
fi

# set a fancy prompt (non-color, unless we know we "want" color)
case "$TERM" in
    xterm-color) color_prompt=yes;;
esac

# uncomment for a colored prompt, if the terminal has the capability; turned
# off by default to not distract the user: the focus in a terminal window
# should be on the output of commands, not on the prompt
#force_color_prompt=yes

if [ -n "$force_color_prompt" ]; then
    if [ -x /usr/bin/tput ] && tput setaf 1 >&/dev/null; then
	# We have color support; assume it's compliant with Ecma-48
	# (ISO/IEC-6429). (Lack of such support is extremely rare, and such
	# a case would tend to support setf rather than setaf.)
	color_prompt=yes
    else
	color_prompt=
    fi
fi

if [ "$color_prompt" = yes ]; then
    PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ '
else
    PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w\$ '
fi
unset color_prompt force_color_prompt

# If this is an xterm set the title to user@host:dir
case "$TERM" in
xterm*|rxvt*)
    PS1="\[\e]0;${debian_chroot:+($debian_chroot)}\u@\h: \w\a\]$PS1"
    ;;
*)
    ;;
esac

# enable color support of ls and also add handy aliases
if [ -x /usr/bin/dircolors ]; then
    test -r ~/.dircolors && eval "$(dircolors -b ~/.dircolors)" || eval "$(dircolors -b)"
    alias ls='ls --color=auto'
    #alias dir='dir --color=auto'
    #alias vdir='vdir --color=auto'

    alias grep='grep --color=auto'
    alias fgrep='fgrep --color=auto'
    alias egrep='egrep --color=auto'
fi

# some more ls aliases
alias ll='ls -alF'
alias la='ls -A'
alias l='ls -CF'

# Add an "alert" alias for long running commands.  Use like so:
#   sleep 10; alert
alias alert='notify-send --urgency=low -i "$([ $? = 0 ] && echo terminal || echo error)" "$(history|tail -n1|sed -e '\''s/^\s*[0-9]\+\s*//;s/[;&|]\s*alert$//'\'')"'

# Alias definitions.
# You may want to put all your additions into a separate file like
# ~/.bash_aliases, instead of adding them here directly.
# See /usr/share/doc/bash-doc/examples in the bash-doc package.

if [ -f ~/.bash_aliases ]; then
    . ~/.bash_aliases
fi

# enable programmable completion features (you don't need to enable
# this, if it's already enabled in /etc/bash.bashrc and /etc/profile
# sources /etc/bash.bashrc).
if [ -f /etc/bash_completion ] && ! shopt -oq posix; then
    . /etc/bash_completion
fi

#set android sdk
export SDK_ROOT=/home/jianjie/Android/adt-bundle-linux-x86-20131030/sdk
export PATH=$PATH:$SDK_ROOT/tools:$SDK_ROOT/platform-tools

#set android ndk
export NDK_ROOT=/home/jianjie/Android/android-ndk-r9b
export PATH=$PATH:$NDK_ROOT

#set eclipse
export ECLIPSE=/home/jianjie/Android/adt-bundle-linux-x86-20131030/eclipse
export PATH=$PATH:$ECLIPSE

系統環境變數

開啟終端並輸入：
sudo gedit /etc/environment
2
輸入使用者密碼。這時輸入的密碼是不可見的。
3
如圖，在PATH="...."的末尾處新增：
：/opt/EmbedSky/4.3.3/bin
其中/opt/EmbedSky/4.3.3/bin為你自己需要設定的環境變數路徑

PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/home/proud/Android/adt-bundle-linux-x86-20140321/sdk/platform-tools"

你可以自己加上指定的多個路徑，中間用冒號隔開。環境變數更改後，在使用者下次登陸時生效，

如果想立刻生效，則可執行下面的語句：    

終端執行 $source/etc/environment

也可修改
然後執行$sudo gedit /etc/profile

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