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：
- 读取
/etc/profile系统配置文件 - 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：
- 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!
- 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。
~/.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
~/.bash_login
centos中不存在~/.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
