Bash and Linux Tool
工具
标准输入输出
Command | Description |
---|---|
echo |
echo "Hello world!" > hello.sh |
printf |
printf "Test the code %d times, and it still can fail the %d-th time." 100 101 |
stdout stderr | ls 1> /tmp/ls.stdout 2> /tmp/ls.stderr |
&& ||
|
mkdir /tmp/good || echo "failed to create folder /tmp/good" short-circuiting |
$(this_is_a_command) or ``
|
touch `seq 1 3` or touch $(seq 1 3)
|
文件系统
-
工作目录(working directory)
Command Description pwd
ls
cd
du
du -sh *
display disk usage statisticsdf
df -h /mnt
display free disk space -
查找文件
Command Description find
find . -type f
找到本目录下所有的文件并输出到屏幕 (包括子目录,下同)-name
:find . -name "*.jpg"
-maxdepth
:find -maxdepth 1
-
文件操作(移动、拷贝、创建文件夹)
Command Description cp
mv
rm
mkdir
rmdir
在~/.bashrc文件中,加入下面的命令: alias cp='cp -i'
alias rm='rm -i'
alias mv='mv -i'
-i
: 如果命令会删除或者覆盖文件,会提示用户confirm。chmod
chmod a-w somefile
把somefile的所有写权限去掉ln
ln -s $src $dest
创建一个软链接$dest, 它指向的原文件在$src
文件内容
-
查看文件
Command Description cat
cat <file>
head
tail
head -n <file>
less
more
less
是more
的升级版,推荐使用less
diff
diff file1 file2
md5sum
md5sum <file>
计算文件的md5码,用来比较本机和远程文件是否相同 -
文件内容操作
Command Description cut
cut -f1,3 file1
cut out selected portions of each line of a file-b
按字节
-f
显示某几列bc
echo "1.212*3" | bc
任意精度的计算器wc
find . -name "*.jpg" | wc -l
数出本目录下所有的jpg文件数量sort
sort a.list > a.sort
对文件a.list排序并写到a.sort-u
: 去重
-k
: sort -k2,2 a.list, 按第2列排序-n
: 按数字排序-V
:可以理解为加强版的按数字排序-r
: 倒序-R
: 随机uniq
cat list1 list2 | sort | uniq > final.list
将list1, list2合并,排序后去重,写到final.list
(其实sort一个命令就够了)
-c
: 用来统计很方便
-u
-d
sed
sed "s@origin@corrected@" a.list -i
将a.list中每行出现的第一个origin替换为corrected
-i
: inplace change
sed -i "s/old/new/g" `grep old -rl /www`
将/www
路径下递归的所有文件中包含old
字符串的文件中的old
都替换成new
awk
awk -F'_' '{print $1}' a.list
将a.list中每行按'_'分隔,每行输出分隔后的第一个字符串,例如1_2_3
->1
xargs
find . -name "*.jpg" | xargs -i rm {}
find . -name "*.jpg" | xargs rm
找到本目录下所有的jpg文件并删除-P
: 多进程
-n
: 一般配合"-P"参数comm
comm -23 a.sort b.sort
输出在a中,不在b中的行grep
cat a.list | grep png
找到a.list中包含png的行
-R
递归查找
-n
列出行号
-l
列出匹配的文件名
-a
-o
-i
不区分大小写
grep "abc" . -nr
查找当前路径下含有“abc”的文件,列出文件名,行号和匹配内容
grep "abc" . -lr
查找当前路径下含有“abc”的文件,列出文件名rev
rev <file>
find . -type f | rev | cut -d'/' -f1 | rev # revcut'/'
reverse the file(or reverse the stdin if no file provided)
系统相关
Command | Description |
---|---|
htop top
|
查看各个进程的实时CUP占用率、内存使用,进程ID,命令行,启动时间,用户等信息。以及机器整体的CPU占用率和内存使用情况。 |
ps |
ps aux ps auxf
|
dstat |
系统资源统计。可以查看每秒的CPU,磁盘读写,网络出入等信息 |
nvidia-smi |
查看GPU的状态 |
ssh |
|
scp |
scp -r $scr $dest 机器之间复制文件 |
rsync |
rsync -avzP $src $dest 和scp接近,文件传输工具。特别适用于大量小文件场合,此时速度会明显快于scp。 -e : rsync -avhP -e "ssh -carcfour" 可以指定ssh参数,如端口/证书等 |
tmux |
https://gist.github.com/MohamedAlaa/2961058 tmux is a terminal multiplexer,你会经常在服务器上工作,应该尽快掌握tmux |
kill pkill killall
|
kill <process_id> kill -9 <process_id> killall python pkill _unittest 杀死进程 |
后台运行相关 |
./a_time_comsuming_process &> 1.log jobs fg (ctrl-z)bg (ctrl-z) |
网络相关
Command | Description |
---|---|
netstat |
netstat -anp|grep <port> 网络详细信息 |
lsof |
lsof -i:<port> |
ping |
ping www.baidu.com |
ifconfig |
常用工具
Command | Description |
---|---|
wget |
wget http://some.server.com/thewantedarticle.pdf -O /tmp/local.pdf 下载工具 |
curl |
|
jq |
用于解析json $ echo '{"key1":"value1","key2":"value2"}' | jq '.key2' "value2"
|
parallel |
用于并行执行多个相近的命令 cat 20urls.list | parallel -j 4 wget -q {}
|
xargs |
xargs 非常强大 find . -type f |grep '2018/03' | xargs -I {} wc -l {} find . -type f |grep '2018/03' | xargs wc -l
|
Linux Package Manager
Command | Description |
---|---|
sudo apt-get update |
更新源列表中的软件列表 |
sudo apt-get upgrade |
把本地已安装的软件,与刚下载的软件列表里对应软件进行对比,如果发现已安装的软件版本太低,就会提示你更新。 |
Bash脚本语法
"#!": shebang。使用chmod +x file
使sh脚本文件可以运行。
#!/bin/bash
变量
-
基本用法
des="awe and cool" echo $des echo ${des} echo "This is ${des}"
-
内置变量
$0
,$1
,$2
...: 脚本参数 -
输出赋值
ret=`cat readme.txt` echo $ret ret=$(cat readme.txt) echo $ret
-
运算
-
let:
let "a = 5 + 6" echo $a x=11 y=22 let "z = x * y" echo $z
-
expr:
$ expr 5 + 6 11 $ foo=$(expr 5 + 6) $ echo $foo 11
注意:运算符和各个数字之间需要有空格
-
双括号
a=$((5+6))
-
判断语句
if <condition> then <cmd> else <cmd> fi
tmp=35 if [ ${tmp} -ge 30 ] then echo "It's too hot" fi
| Operator | Description |
| :------------- |:-------------|
|`! EXPRESSION`| The EXPRESSION is false.
|`-n STRING`| The length of STRING is greater than zero.
|`-z STRING`|The lengh of STRING is zero (ie it is empty).
|`STRING1 = STRING2`| STRING1 is equal to STRING2
|`STRING1 != STRING2`| STRING1 is not equal to STRING2
|`INTEGER1 -eq INTEGER2`| INTEGER1 is numerically equal to INTEGER2
|`INTEGER1 -gt INTEGER2`| INTEGER1 is numerically greater than INTEGER2
|`INTEGER1 -lt INTEGER2`| INTEGER1 is numerically less than INTEGER2
|`-d FILE`| FILE exists and is a directory.
|`-e FILE`| FILE exists.
|`-r FILE`| FILE exists and the read permission is granted.
|`-s FILE`| FILE exists and it's size is greater than zero (ie. it is not empty).
|`-w FILE`| FILE exists and the write permission is granted.
|`-x FILE`| FILE exists and the execute permission is granted.
test命令:
```bash
$ test 5 -ge 4
$ echo $?
0
```
test命令的结果,0表示true或命令运行成功;1表示false或运行失败。
-
布尔运算
&&
,||
if [ $code_review = "pass" ] && [ $regression_test = "pass" ] then echo "ship it!" fi
-
循环语句
for var in <list> do <cmd> done
for name in John, Emma, Tom do echo "My name is $name" done for num in {1..10} do echo "count $num" done for ((i=0; i<10; i++)) do echo "count $i" done
-
until语句
until [ some_test ] do <cmd> done
suffix=1 until [ ! -e "foo${suffix}" ] do let suffix++ done echo "The file name foo${suffix} is good.
-
break
-
continue
-
函数
function_name () {
<commands>
}
discuss_langauges() {
language1=$1
language2=$2
echo "$1 is a good language."
echo "$2 is also a good language."
}
discuss_langauges c++ python
调用不需括号
find_cpp_files() {
local folder=$1
local ret=$(find ${folder} -name '*.cpp' | wc -l)
return $ret
}
folder=/home/hchen/code/ficus/common/machine_learning
find_cpp_files $folder
num_files=$?
echo "There are ${num_files} cpp files in ${folder}"
调试技巧
set -e
set -x
实用案例
- Test if a comand outputs an empty string:
if [[ $(YOUR_COMMAND)]]
# ls directory
if [[ $(ls -A) ]]; then
echo "there are files"
else
echo "no files found"
fi
# grep file context
if [[ $(cat file | grep key_word) ]]; then
echo "find key_word in the file"
then
echo "Not found"
fi
- Check whether the last command complete successfully.
$?
: the exit code of the last command (zero for success, non-zero for failure).
files=$(ls -A)
if [[ $? != 0 ]]; then
echo "Command failed."
elif [[ $files ]]; then
echo "Files found."
else
echo "No files found."
fi
网友评论