Search

Search IconIcon to open search

命令行指南

Last updated Jul 9, 2024

# 常用命令行工具
常用命令行工具

  • 文件管理 cd, pwd, mkdir, rmdir, , cp, rm, mv,

  • 文件控制 cat, more, less, file,

  • 输入输出控制 - , 管道 |, ,

  • 文本处理 VIM, grep/, , , , , , , , tr

  • 系统监控 jobs, ps, top, kill, free, dmesg, lsof

  • 查文档 tldr, man

  • 窗口控制 tmux

# 文件管理

# ls
command: ll

ll 等于 ls -al

# tar

tar

  • .tar is a sinple bundle of files, without compression
  • .tar.gz with compression

usage

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11

# [c]reate an archive and write it to a [f]ile:
tar cf path/to/target.tar path/to/file1 path/to/file2 ...

# [c]reate a g[z]ipped archive and write it to a [f]ile:
tar czf path/to/target.tar.gz path/to/file1 path/to/file2 ...

# E[x]tract a (compressed) archive [f]ile into the current directory [v]erbosely:
tar xvf path/to/source.tar[.gz|.bz2|.xz]

# E[x]tract a (compressed) archive [f]ile into the target directory:
tar xf path/to/source.tar[.gz|.bz2|.xz] --directory=path/to/directory

# 文件控制

# head/tail

head -n5

# find

find

 1
 2
 3
 4
 5
 6
 7
 8
 9
10

# Find all directories named src
find . -name src -type d
# Find all python files that have a folder named test in their path
find . -path '*/test/*.py' -type f
# Find all files modified in the last day
find . -mtime -1
# Find all zip files with size in range 500k to 10M
find . -size +500k -size -10M -name '*.tar.gz'
# Find directories matching a given name, in case-insensitive mode:
find root_path -type d -iname '*lib*

1
2
3
4

# Delete all files with .tmp extension
find . -name '*.tmp' -exec rm {} \;
# Find all PNG files and convert them to JPG
find . -name '*.png' -exec convert {} {}.jpg \;

-print0

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12

find -name "*.html"
./3.html
./4.html
./5.html
./1.html
./2.html

find -name "*.html" -print0                      
./3.html./4.html./5.html./1.html./2.html

# 这样就能统计每个文件的字数
find -name "*.html" -print0 | xargs -0 wc -l

# 输入输出控制

# 重定向
重定向

  • < 以某文件的内容作为输入流

  • >> 追加模式将输出流重定向到某文件

  • > 覆盖模式将输出流重定向到某文件

  • &>> = >> + 2>&1

    • command >> filename 2>&1 is equivalent to command &>> filename

  • stdout 的 fd 是 1, stderr 的 fd 是 2

用重定向复制
1

cat < 1.txt >> 2.txt

会将 1 的内容追加到 2.txt 末尾

# sort

sort -n -k

1
2

# 根据 (n)umeric sort by c(k)olumn 1 to 1
sort | uniq -c | sort -nk1,1

其实默认就是 -k1,1

# wc

wc

wc -l

# bc

berkeley count?

calculate a string expression

1
2
3

echo '1+2+3' | bc -l #3

command | uniq -c | awk '{print $1}' | paste -sd+ | bc -l

# uniq

sort | uniq

# cut
example
1

curl --head --silent google.com |grep -i content-length | cut --delimiter=' ' -f2
  • 以空格为分隔符, 第 2 个 field
  • out: 219
  • 前两部分的结果是 ‘Content-Length: 219’

# tee

tee

  • takes an input, write it to STDOUT and also a file

example

1

echo "hello" | tee 1.txt

# xargs

xargs

  • | can redirect STDOUT to STDIN, xargs can redirect STDOUT to arguments
  • -0 means delimited by \0, usually used after find -print0

example

1

ls | xargs chmod u+x

# 文本处理

# rg

 
1
2
3
4
5
6
7
8

# Find all python files where I used the requests library
rg -t py 'import requests'
# Find all files (including hidden files) without a shebang line
rg -u --files-without-match "^#\!"
# Find all matches of foo and print the following 5 lines
rg foo -A 5
# Print statistics of matches (# of matched lines and files )
rg --stats PATTERN

# awk

a column-based(whitespace separated) string processor

print the second column

1
2

command | awk '{print $2}' | paste -sd,
# 1234,root,ad,df

paste in (s)ingle line, (d)elimited by ‘,’

conditions

1
2
3
4

# print whole rows which
# first column is 1
# and sec. column match the /regex/
command | awk '$1 == 1 && $2 ~ /^c.*e$/ {print $0}'

setup and teardown

1
2

# count rows that meet the condition
command | awk 'BEGIN { ctr = 0 } $1 == 1 && $2 ~ /^c.*e$/ { ctr += 1 } END { print ctr }'

当然, 单纯数行用 wc 更快, 但你应该知道 awk 也是可以做到的

# sed

a string editor

sed 默认对每一行分别操作

建议默认使用 sed -E, 这是更现代化的模式

  • sed -E 's/(ab)*//g'
  • = `sed ’s/(ab)*//g'

sed substitude

1
2
3

echo 'aba' | sed 's/[ab]//'
# ba
# 默认只 replace 一次

在这个例子中, ssh.log 是一个 nginx 日志(大概), sed 对 cat 的展示结果进行了 正则替换

1

cat ssh.log | sed 's/.*Disconnected from //' | less

# regex

互动练习: regex101.com(已通)

替换是 默认 greedy 的, .* non-greedy 需要 .*?

# 快捷键

以下快捷键以 Linux 为主, Powershell 和 Mac Terminal 不一定全都可用

键入 man readline 可以查看 Bash 中的默认快捷键

  • <c-a> 移动到行首
  • <c-e> 行尾
  • <c-h> 删除前一个字符
  • <c-w> 删除前一个单词
  • <c-u> 删除光标前的内容
  • <c-k> 删除光标后的内容
  • <c-r> 历史命令
  • <alt-b> 向后一个单词
  • <alt-f> 向前一个单词
  • <c+l> 等于 clear, 清屏
  • <c+d> 约等于退出? 可用于 exit python | WIN 是 <c+z>enter

# linux 文件系统
  • sys 是内存参数
  • sudo echo 500 > brightness 会失败因为sudo 只运行 了 echo , 而不是 sudo 打开 brightness
    • sudo su 会换成 root
    • echo 500 | sudo tee brightness 就可行, 因为用 sudo 执行了 tee, tee 打开的 brightness

# Shell scripting

# 变量

赋值与调用

  • foo=bar
  • echo $foo

单引号和双引号

单引号中的变量不会被展开

特殊变量

  • $0 指程序本身

  • $1 to $9 Arguments to the script,

  • $$ PID

  • $? returns result code of last command

  • $# 参数数量

  • $_ 表示重复上一条命令的变量

  • $_ Last argument from the last command. If you are in an interactive shell, you can also quickly get this value by typing Esc followed by . or Alt+.

  • $@ 是 $1, $2… 的集合

  • sudo !! 展开就是上一条命令, 在执行必要用 sudo 的命令好用

  • $((expression)) stores the result, example: var=$((3+9))

  • foo=$(pwd) 中的 $() 是 pwd 命令结果

Practices

与上一条参数相同的话:

1
2

mkdir test
cd $_

遍历程序参数:

1
2

for file in "$@":
    ...

对必须接受文件的为参数的程序很有用:

  • ls 的结果会存在临时文件里交给 cat
1

cat <(ls)

遍历当前目录很简单:

1

for file in $(ls)

快速比较目录:

1

diff <(ls foo) <(ls bar)

shebang

1

#!/bin/bash

特殊变量的使用

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15

#!/bin/bash

echo "Starting program at $(date)" # Date will be substituted

echo "Running program $0 with $# arguments with pid $$"

for file in "$@"; do
    grep foobar "$file" > /dev/null 2> /dev/null 
    # When pattern is not found, grep has exit status 1
    # We redirect STDOUT and STDERR (2>) to a null register since we do not care about them
    if span> ; then
        echo "File $file does not have any foobar, adding one"
        echo "# foobar" >> "$file"
    fi
done

# 正则展开

{}

1
2
3
4
5

# This creates files foo/a, foo/b, ... foo/h, bar/a, bar/b, ... bar/h
touch {foo,bar}/{a..h}

# This creates files a1, a2, a3, a4, a5
touch a{1..5}
  • {}{} will create cartesian product

# test
  • -eq, -ge, -gt, -le, -lt, -ne
  • -a, -o
  • [] 是可行的, 但使用 [[]] 会 更好

man test for more info

1
2
3
4
5
6
7
8

#!/bin/bash
i=1
while span>  ; do # -le
   echo "$i"
  (( i += 1 ))
done

if [ $a -gt 40 -a $b -lt 6 ] # if a > 40 and b < 6

# control

 
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13

read x
read y

if [ $x -gt $y ]
then
echo X is greater than Y
elif [ $x -lt $y ]
then
echo X is less than Y
elif [ $x -eq $y ]
then
echo X is equal to Y
fi

1
2
3
4
5
6

#!/bin/bash

for i in {1..5}
do
    echo $i
done

1
2
3
4
5
6

#!/bin/bash
i=1
while span>  ; do
   echo "$i"
  (( i += 1 ))
done

# Data wrangling

sed, awk sort, wc, bc,

统计 syslog 中 各用户名登录数据, 并用 R 进行统计学分析

或者画图

批量卸载不需要的版本号

set loglevel to panic, take a single frame from webcam device as a image, print to STDOUT rather than give a file(-), convert read from STDIN(-), convert to grey colorspace and write to STDOUT(-), compress and send to server tsp, make copies both file and STDOUT, bring it back to local stream and feh displays

show on server tsp

Backlinks

  • No backlinks found

Interactive Graph