Linux shell script programming All In One

Linux shell script programming All In One

shell 脚本编程

Linux 系统中登录 shell 的时候，会从下面的 5 个启动文件里读取命令；

# 系统级，所有登录用户都会先启动这个文件
$ cat /etc/profile

# 用户级，按照Linux 发行版中实际存在的文件个数，依次进行启动
$ cat $HOME/.bash_profile
$ cat $HOME/.bashrc
$ cat $HOME/.bash_login
$ cat $HOME/.profile

.sh => Bourne shell => bash

.csh => c shell

https://www.gnu.org/software/bash/manual/bash.pdf

Linux 进程信号量

process signal

Linux shell commands argument styles

Linux shell 命令行参数风格

Unix 风格, AT&T，-单破折号
BSD 风格, 加州大学伯克利分校, 没有破折号
GNU 风格, -- 双破折号

Unix
BSD
GNU

https://unix.org

https://www.bsd.org/

https://www.gnu.org

shell types

shell 类型 / shell 种类

# $ which shell

$ which bash
$ which sh
$ which zsh

系统	截图
Raspberry Pi
macOS

启动文件

1. 系统的 shell 启动配置文件 /etc/profile

$ cat /etc/profile

# /etc/profile: system-wide .profile file for the Bourne shell (sh(1))
# and Bourne compatible shells (bash(1), ksh(1), ash(1), ...).

if [ "$(id -u)" -eq 0 ]; then
  PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
else
  PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/games:/usr/games"
fi
export PATH

if [ "${PS1-}" ]; then
  if [ "${BASH-}" ] && [ "$BASH" != "/bin/sh" ]; then
    # The file bash.bashrc already sets the default PS1.
    # PS1='\h:\w\$ '
    if [ -f /etc/bash.bashrc ]; then
      . /etc/bash.bashrc
    fi
  else
    if [ "$(id -u)" -eq 0 ]; then
      PS1='# '
    else
      PS1='$ '
    fi
  fi
fi

if [ -d /etc/profile.d ]; then
  for i in /etc/profile.d/*.sh; do
    if [ -r $i ]; then
      . $i
    fi
  done
  unset i
fi

# 配置文件目录 `/etc/profile.d`
$ ls -al /etc/profile.d

pi@raspberrypi:~ $ ls -al /etc/profile.d
总用量 36
drwxr-xr-x   2 root root 4096  4月 10 01:31 .
drwxr-xr-x 123 root root 4096  4月 18 12:03 ..
-rw-r--r--   1 root root   95  4月 29  2019 at-dbus-fix.sh
-rw-r--r--   1 root root  726  8月 12  2020 bash_completion.sh
-rw-r--r--   1 root root  349 12月 18  2020 im-config_wayland.sh
-rw-r--r--   1 root root  324  6月  8  2022 sshpwd.sh
-rw-r--r--   1 root root 1384  2月 18  2021 vte-2.91.sh
-rw-r--r--   1 root root  966  2月 18  2021 vte.csh
-rw-r--r--   1 root root  450  7月 22  2019 wifi-check.sh
pi@raspberrypi:~ $ 

2. 用户的 shell 启动配置文件 $HOME/.profile

$ cat $HOME/.profile
# 等价于
$ cd ~ && cat .profile

# ~/.profile: executed by the command interpreter for login shells.
# This file is not read by bash(1), if ~/.bash_profile or ~/.bash_login
# exists.
# see /usr/share/doc/bash/examples/startup-files for examples.
# the files are located in the bash-doc package.

# the default umask is set in /etc/profile; for setting the umask
# for ssh logins, install and configure the libpam-umask package.
#umask 022

# if running bash
if [ -n "$BASH_VERSION" ]; then
    # include .bashrc if it exists
    if [ -f "$HOME/.bashrc" ]; then
	. "$HOME/.bashrc"
    fi
fi

# set PATH so it includes user's private bin if it exists
if [ -d "$HOME/bin" ] ; then
    PATH="$HOME/bin:$PATH"
fi

# set PATH so it includes user's private bin if it exists
if [ -d "$HOME/.local/bin" ] ; then
    PATH="$HOME/.local/bin:$PATH"
fi

echo "每次登录自动执行脚本 ✅"
bash /home/pi/Desktop/ip-program.sh

demos

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parent shell vs child shell

eric@rpi4b:~ $ printenv NVM_USER_ENV
eric@rpi4b:~ $ printenv | grep NVM_USER_ENV
eric@rpi4b:~ $ printenv | grep NVM_USER
NVM_USER=xgqfrms_pi4b
eric@rpi4b:~ $ printenv NVM_USER
xgqfrms_pi4b
eric@rpi4b:~ $ env NVM_USER
env: “NVM_USER”: 没有那个文件或目录
eric@rpi4b:~ $ export NVM_USER_ENV=eric_env
eric@rpi4b:~ $ printenv | grep NVM_USER
NVM_USER_ENV=eric_env
NVM_USER=xgqfrms_pi4b
eric@rpi4b:~ $ export NVM_USER_ENV=eric_env_new
eric@rpi4b:~ $ printenv | grep NVM_USER
NVM_USER_ENV=eric_env_new
NVM_USER=xgqfrms_pi4b
eric@rpi4b:~ $ bash
fix vim bug ✅
eric@rpi4b:~ $ echo $NVM_USER
xgqfrms_pi4b
eric@rpi4b:~ $ printenv | grep NVM_USER
NVM_USER_ENV=eric_env_new
NVM_USER=xgqfrms_pi4b
eric@rpi4b:~ $ echo $NVM_USER_ENV
eric_env_new
eric@rpi4b:~ $ export NVM_USER_ENV=eric_env_child
eric@rpi4b:~ $ echo $NVM_USER_ENV
eric_env_child
eric@rpi4b:~ $ exit
exit
eric@rpi4b:~ $ printenv | grep NVM_USER
NVM_USER_ENV=eric_env_new
NVM_USER=xgqfrms_pi4b
eric@rpi4b:~ $ 
eric@rpi4b:~ $ printenv | grep NVM_USER
NVM_USER_ENV=eric_env_new
NVM_USER=xgqfrms_pi4b

eric@rpi4b:~ $ printenv | grep NVM_USER
NVM_USER_ENV=eric_env_new
NVM_USER=xgqfrms_pi4b
eric@rpi4b:~ $ bash
fix vim bug ✅
eric@rpi4b:~ $ echo $NVM_USER_ENV
eric_env_new
eric@rpi4b:~ $ export NVM_USER_ENV_CHILD=child_shell_env
eric@rpi4b:~ $ echo $NVM_USER_CHILD

eric@rpi4b:~ $ echo $NVM_USER_ENV_CHILD
child_shell_env
eric@rpi4b:~ $ exit
exit
eric@rpi4b:~ $ echo $NVM_USER_ENV_CHILD

eric@rpi4b:~ $ printenv | grep NVM_USER
NVM_USER_ENV=eric_env_new
NVM_USER=xgqfrms_pi4b
eric@rpi4b:~ $ 

raspi-config

# GUI 交互式命令行界面
$ sudo raspi-config

在本质上还是直接修改 /boot/config.txt 配置文件

https://www.raspberrypi.com/documentation/computers/configuration.html#the-raspi-config-tool

refs

https://github.com/xgqfrms?tab=repositories&q=shell&type=&language=&sort=

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