1. 背景

在看shell變量的時(shí)候引起了興趣: 局部變量，全局變量，環(huán)境變量，shell的配置文件，參考博客:

http://c.biancheng.net/view/773.html

2. 交互式與非交互式

參考博客:

shell的兩個(gè)屬性:是否交互式(interactive), 是否登錄(login) - 知乎?

man bash:

通常的理解是:

?man手冊(cè)中給我們提供了怎么判斷交互與非交互的方法:

?所以我看看我自己的shell是否是交互式的:

liaojunwu@liaojunwu-virtual-machine:~$ echo $PS1
\[\e]0;\u@\h: \w\a\]${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$
liaojunwu@liaojunwu-virtual-machine:~$ 
liaojunwu@liaojunwu-virtual-machine:~$ echo $-
himBH
liaojunwu@liaojunwu-virtual-machine:~$ 

?3. 登錄與非登陸

man bash:

通常的理解是:

?su和su -命令的區(qū)別參考博客:?一分鐘知識(shí)點(diǎn)：linux命令之su 和 su -?

可以用shopt login_shell的方法來看看shell是否設(shè)置了login_shell選項(xiàng)，我看看我自己的shell:

liaojunwu@liaojunwu-virtual-machine:~$ shopt login_shell
login_shell    	off
liaojunwu@liaojunwu-virtual-machine:~$ 
liaojunwu@liaojunwu-virtual-machine:~$ su - liaojunwu --login
密碼： 
liaojunwu@liaojunwu-virtual-machine:~$ 
liaojunwu@liaojunwu-virtual-machine:~$ 
liaojunwu@liaojunwu-virtual-machine:~$ shopt login_shell
login_shell    	on
liaojunwu@liaojunwu-virtual-machine:~$ 

?4. 為什么要知道這兩種屬性？

因?yàn)樯婕暗絪hell配置方式的不同，繼續(xù)看man手冊(cè):

交互與登錄屬性一共有四種組合，我們只看三種:

登錄交互與登錄非交互: bash配置shell的順序是:

/etc/profile->~/.bash_profile->~/.bash_login->~/.profile->~/.bashrc

展開/etc/profile又可以看到登錄交互會(huì)去配置/etc/bash.bashrc

# /etc/profile: system-wide .profile file for the Bourne shell (sh(1))
# and Bourne compatible shells (bash(1), ksh(1), ash(1), ...).if [ "$PS1" ]; thenif [ "$BASH" ] && [ "$BASH" != "/bin/sh" ]; then# The file bash.bashrc already sets the default PS1.# PS1='\h:\w\$ 'if [ -f /etc/bash.bashrc ]; then. /etc/bash.bashrcfielseif [ "`id -u`" -eq 0 ]; thenPS1='# 'elsePS1='$ 'fifi
fiif [ -d /etc/profile.d ]; thenfor i in /etc/profile.d/*.sh; doif [ -r $i ]; then. $ifidoneunset i
fiexport PATH=$PATH:/usr/local/arm/gcc-linaro-4.9.4-2017.01-x86_64_arm-linux-gnueabihf/bin

非登錄交互時(shí): bash的配置順序是:

/etc/bash.bashrc->~/.bashrc

我們可以看到不論是/etc/bash.bashrc還是~/.bashrc，都要求是交互模式才行:

?

?5. 驗(yàn)證

登錄交互:?/etc/profile->/etc/bash.bashrc->~/.bash_profile->~/.bash_login->~/.profile->~/.bashrc

liaojunwu@liaojunwu-virtual-machine:~$ 
liaojunwu@liaojunwu-virtual-machine:~$ echo $PS1
\[\e]0;\u@\h: \w\a\]${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$
liaojunwu@liaojunwu-virtual-machine:~$ 
liaojunwu@liaojunwu-virtual-machine:~$ 
liaojunwu@liaojunwu-virtual-machine:~$ 
liaojunwu@liaojunwu-virtual-machine:~$ shopt login_shell
login_shell    	on
liaojunwu@liaojunwu-virtual-machine:~$ 
liaojunwu@liaojunwu-virtual-machine:~$ 
liaojunwu@liaojunwu-virtual-machine:~$ logout
liaojunwu@liaojunwu-virtual-machine:~$ exit
注銷
liaojunwu@liaojunwu-virtual-machine:~$ exit
注銷
liaojunwu@liaojunwu-virtual-machine:~$ exit
注銷
liaojunwu@liaojunwu-virtual-machine:~$ su - root
密碼： 
[DEBUG]in /etc/profile!
[DEBUG]in /etc/bash.bashrc!
root@liaojunwu-virtual-machine:~# 
root@liaojunwu-virtual-machine:~# 
root@liaojunwu-virtual-machine:~# su - liaojunwu --login
[DEBUG]in /etc/profile!
[DEBUG]in /etc/bash.bashrc!
[DEBUG]in ~./profile!
[DEBUG]in ~./bashrc !
liaojunwu@liaojunwu-virtual-machine:~$ 

非登錄交互:?/etc/bash.bashrc->~/.bashrc

[DEBUG]in /etc/bash.bashrc!
[DEBUG]in ~./bashrc !
liaojunwu@liaojunwu-virtual-machine:~$ echo $-
himBH
liaojunwu@liaojunwu-virtual-machine:~$ shopt login_shell
login_shell    	off
liaojunwu@liaojunwu-virtual-machine:~$ 
liaojunwu@liaojunwu-virtual-machine:~$ 
liaojunwu@liaojunwu-virtual-machine:~$ 
liaojunwu@liaojunwu-virtual-machine:~$ 
liaojunwu@liaojunwu-virtual-machine:~$ bash -i
[DEBUG]in /etc/bash.bashrc!
[DEBUG]in ~./bashrc !
liaojunwu@liaojunwu-virtual-machine:~$ 

6. PS1變量

參考博客:?bash下變量PS1的完整理解_ps1變量_whowin的博客-CSDN博客