Linux配置文件

Linux Login Shell配置文件读取

在我们登录Linux时，使用的shell就是login shell, login shell通过读取不同的配置文件，这些配置文件定义了各种别名，变量，赋予了我们登录后就能享受各种别名和变量的权利。login shell读取配置文件的流程如下：

  1. 读取/etc/profile系统配置文件
  2. 读取~/.bash_profile,~/.profile,~/.bash_login用户配置文件中的任何一个，其中读取顺序为~/.bash_profile ~/.bash_login ~/.profile
    如果其中一个文件存在那么就不会执行下面的文件，比如检查到~/.bash_profile文件存在，那么就不会执行~/.bash_login和~/.profile

Linux Nologin Shell配置文件读取

nologin shell仅会读取~/.bashrc配置文件

系统配置文件

系统配置文件/etc/profile所做事情为：

  1. 设置环境变量
    • PATH:会依据 UID 决定 PATH 变量要不要含有 sbin 的系统指令目录;
    • MAIL:依据帐号设置好使用者的 mailbox 到 /var/spool/mail/帐号名;
    • USER:根据使用者的帐号设置此一变量内容;
    • HOSTNAME:依据主机的 hostname 指令决定此一变量内容;
    • HISTSIZE:历史命令记录笔数。CentOS 7.x 设置为 1000 ;
    • umask:包括 root 默认为 022 而一般用户为 002 等!
  2. 执行/etc/profile.d/*.sh
    • colorls.sh定义颜色
    • lang.sh定义语系
    • vim.shvim命令的别名
    • which2.shwhich命令别名
# /etc/profile

# System wide environment and startup programs, for login setup
# Functions and aliases go in /etc/bashrc

# It's NOT a good idea to change this file unless you know what you
# are doing. It's much better to create a custom.sh shell script in
# /etc/profile.d/ to make custom changes to your environment, as this
# will prevent the need for merging in future updates.

pathmunge () {
    case ":${PATH}:" in
        *:"$1":*)
            ;;
        *)
            if [ "$2" = "after" ] ; then
                PATH=$PATH:$1
            else
                PATH=$1:$PATH
            fi
    esac
}


if [ -x /usr/bin/id ]; then
    if [ -z "$EUID" ]; then
        # ksh workaround
        EUID=`id -u`
        UID=`id -ru`
    fi
    USER="`id -un`"
    LOGNAME=$USER
    MAIL="/var/spool/mail/$USER"
fi

# Path manipulation
if [ "$EUID" = "0" ]; then
    pathmunge /sbin
    pathmunge /usr/sbin
    pathmunge /usr/local/sbin
else
    pathmunge /usr/local/sbin after
    pathmunge /usr/sbin after
    pathmunge /sbin after
fi

HOSTNAME=`/bin/hostname 2>/dev/null`
HISTSIZE=1000
if [ "$HISTCONTROL" = "ignorespace" ] ; then
    export HISTCONTROL=ignoreboth
else
    export HISTCONTROL=ignoredups
fi

export PATH USER LOGNAME MAIL HOSTNAME HISTSIZE HISTCONTROL

# By default, we want umask to get set. This sets it for login shell
# Current threshold for system reserved uid/gids is 200
# You could check uidgid reservation validity in
# /usr/share/doc/setup-*/uidgid file
if [ $UID -gt 199 ] && [ "`id -gn`" = "`id -un`" ]; then
    umask 002
else
    umask 022
fi

for i in /etc/profile.d/*.sh ; do
    if [ -r "$i" ]; then
        if [ "${-#*i}" != "$-" ]; then
            . "$i"
        else
            . "$i" >/dev/null 2>&1
        fi
    fi
done

unset i
unset -f pathmunge
HISTTIMEFORMAT="%Y/%m/%d/%H-%M-%S #>"
export HISTTIMEFORMAT

用户配置文件

Linux之所以会有这么多的用户配置文件，是为了使不同操作系统过来的用户能够快速的适应Linux。

  1. ~/.bash_profile
source ~/.bashrc

~/.bashrc中都有什么？

# .bashrc

# User specific aliases and functions

alias rm='rm -i'
alias cp='cp -i'
alias mv='mv -i'
alias ll='ls -l'


# Source global definitions
if [ -f /etc/bashrc ]; then
        . /etc/bashrc
fi
export JAVA_HOME=/home/export/servers/jdk1.6.0_25
export JAVA_BIN=/home/export/servers/jdk1.6.0_25/bin
export PATH=/usr/kerberos/sbin:/usr/kerberos/bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin:/bin:$JAVA_BIN
export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar

可以看到最后执行了/etc/bashrc，看看里面都有什么？

# /etc/bashrc

# System wide functions and aliases
# Environment stuff goes in /etc/profile

# It's NOT a good idea to change this file unless you know what you
# are doing. It's much better to create a custom.sh shell script in
# /etc/profile.d/ to make custom changes to your environment, as this
# will prevent the need for merging in future updates.

# are we an interactive shell?
if [ "$PS1" ]; then
  if [ -z "$PROMPT_COMMAND" ]; then
    case $TERM in
    xterm*)
        if [ -e /etc/sysconfig/bash-prompt-xterm ]; then
            PROMPT_COMMAND=/etc/sysconfig/bash-prompt-xterm
        else
            PROMPT_COMMAND='printf "\033]0;%s@%s:%s\007" "${USER}" "${HOSTNAME%%.*}" "${PWD/#$HOME/~}"'
        fi
        ;;
    screen)
        if [ -e /etc/sysconfig/bash-prompt-screen ]; then
            PROMPT_COMMAND=/etc/sysconfig/bash-prompt-screen
        else
            PROMPT_COMMAND='printf "\033]0;%s@%s:%s\033\\" "${USER}" "${HOSTNAME%%.*}" "${PWD/#$HOME/~}"'
        fi
        ;;
    *)
        [ -e /etc/sysconfig/bash-prompt-default ] && PROMPT_COMMAND=/etc/sysconfig/bash-prompt-default
        ;;
      esac
  fi
  # Turn on checkwinsize
  shopt -s checkwinsize
  [ "$PS1" = "\\s-\\v\\\$ " ] && PS1="[\u@\h \W]\\$ "
  # You might want to have e.g. tty in prompt (e.g. more virtual machines)
  # and console windows
  # If you want to do so, just add e.g.
  # if [ "$PS1" ]; then
  #   PS1="[\u@\h:\l \W]\\$ "
  # fi
  # to your custom modification shell script in /etc/profile.d/ directory
fi

if ! shopt -q login_shell ; then # We're not a login shell
    # Need to redefine pathmunge, it get's undefined at the end of /etc/profile
    pathmunge () {
        case ":${PATH}:" in
            *:"$1":*)
                ;;
            *)
                if [ "$2" = "after" ] ; then
                    PATH=$PATH:$1
                else
                    PATH=$1:$PATH
                fi
        esac
    }

    # By default, we want umask to get set. This sets it for non-login shell.
    # Current threshold for system reserved uid/gids is 200
    # You could check uidgid reservation validity in
    # /usr/share/doc/setup-*/uidgid file
    if [ $UID -gt 199 ] && [ "`id -gn`" = "`id -un`" ]; then
       umask 002
    else
       umask 022
    fi

    # Only display echos from profile.d scripts if we are no login shell
    # and interactive - otherwise just process them to set envvars
    for i in /etc/profile.d/*.sh; do
        if [ -r "$i" ]; then
            if [ "$PS1" ]; then
                . "$i"
            else
                . "$i" >/dev/null 2>&1
            fi
        fi
    done

    unset i
    unset pathmunge
fi
# vim:ts=4:sw=4

等我看完shell script再来告诉你里面都写了啥

  1. ~/.bash_login
    centos中不存在

  2. ~/.profile
    centos中不存在

故最后总结流程如下：


各种文件的执行流程.jpg

使用source读取配置文件

/etc/profile和~/.bash_profile都是需要登出并且登录时，login shell才会去读取的配置文件，source命令可以让配置文件及时生效

source ~/.bash_profile
# or
. ~/.bash_profile
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