Linux common commands-Computer Knowledge-php.cn

Linux common commands

Command 1: pwd

pwd displays the current working path and checks the location.

[root@bunian ~]# pwd
/root

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Command 2: ls

The ls command is very commonly used. ls refers to list, a command to view files or directories. Commonly used after adding parameters:

ls: View all files in the directory
ls -l: Display all information in files and directories
ls -a: List all files, including hidden files, where a means all
ls -R: List all files in the subdirectory, which is equivalent to recursively listing all the contents, which means that all files in the directory will be displayed
ls [0-9]: Display file names and directory names containing numbers

Command 3: cp

cp means copy and is used to copy files. This command can also copy multiple files to the same directory at one time

cp -a: Copy the characteristics of the file together
cp -p: Copy together with the attributes of the file, similar to the -a parameter above, often used for backup
cp -i: If the target file exists, ask before overwriting
cp -r: Recursive continuous copy
cp -u: Copying will only occur when there are differences between the target file and the source file

Command 4: mv

mv means move, which is used to move files, directories or change file names

mv -f: f refers to force, no inquiry will be made before overwriting
mv -i: Ask before overwriting
mv -u: The target file will be updated only when it is newer than the source file

mv 旧文件名 新文件名-- 重命名
mv hello.txt /home/peter-- 移动位置
mv /dir1 /dir2-- 将目录dir1移动到目录dir2中，前提是dir2已经存在，若不存在则改名
mv /dir1/* . -- 将dir1下面的全部文件(*代表全部)移动到当前目录下

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Command 5: rm

rm means remove, which is used to delete files or directories

rm -f: Forced deletion of content without any warning content
rm -i: Interactive mode, ask whether to delete before deleting
rm -r: Recursive deletion, most commonly used to delete all contents in a directory

PS: Use this command with caution! ! !

Command 6: cd

The cd command represents switching directories and can use relative or absolute paths as parameters.

Several commonly used commands for switching paths:

cd /home/user: Switch to the "/home/user" directory
cd: Switch to personal home directory
cd ..: Return to the previous directory
cd ../..: Return to the directory two levels above
cd -: Return to the last directory
cd ~: Return to the user’s home directory

It should be noted that the parent directory of the root directory is itself

Special symbols	Function
~	Represents the home directory of the currently logged in user
~Username	Indicates switching to the home directory of the specified user
–	represents the directory where you were last located
.	represents the current directory
..	Represents the superior directory

Command 7: mkdir

mkdir refers to make directory, which means creating a directory. If the directory exists, an error will be reported.

mkdir test# 创建空白的test目录
mkdir -p test/a/b/c/d# 使用-p参数来递归地创建多个层级目录

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Command 8: touch

The touch command is used to create a blank file or set the time of the file.

Creating a file is simple:

touch bunian.txt  # 创建bunian.txt文件

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The time to set the file is mainly reflected in:

Set the modification time of file content: mtime
File permission or attribute change time: ctime
File reading time: atime

The corresponding parameters are:

parameter	effect
-a	Only modify the "read time" atime
-m	Only modify the "modification time" mtime
-d	Modify both simultaneously

命令9：cat

cat命令主要是用来查看文件的内容，后面跟上我们的文件名即可。通常可以用管道符和命令more或者less进行连用。常用的参数选项：

cat filename：查看文件的全部内容
cat -n filename ：将文件的行数全部显示出来，包含空行
cat -b filename：和-n类似，只是不显示空行
cat -s filename：当遇到有连续两行以上的空白行，就代换为一行的空白行
cat -E：在每行的结尾显示$

命令10：more

more命令的功能和cat命令是类似的，只不过是常用来显示一个长文件，它是以全屏的方式按照分页的方式显示内容。cat命令是整个文件的内容显示在屏幕上，more命令是以分页的方式来显示的。

常用的操作：空白键space跳到下一页，b键则返回上一页。

常用的参数为：

+n ：从第n开始显示文件内容
-n ：屏幕只显示n行数
-s：将连续的空行显示为一行
-u：将文件内容中的下划线去掉
-c：不进行滚屏操作。每次刷新这个屏幕
-l：忽略Ctrl+l换页字符
+/pattern：在每个文档显示前搜寻该字串（pattern），然后从该字串之后开始显示

配合该命令的常用操作：

Enter n：向下翻动n行，默认是1行，可自定义

Ctrl+F：向下滚动一屏

空格键：向下滚动一屏

Ctrl+B：返回上一屏

V：调用vim编辑器

q：推出more命令

more +3 bunian.txt# 从第3行开始显示
more -20 bunian.txt # 屏幕只显示20行
more +/hello bunian.txt # 查询文件中第1次出现hello的位置
more -c -5 file# 每5行显示一次，而且在显示之前先清屏

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如果某个目录下文件过多，我们可以使用more命令来进行分页显示：

ls -l | more -5   # 输出当前目录下的全部文件，并且每页显示5个文件信息

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还有其他的显示文件行数的命令：less、head、tail、tac

tac file# 从最后一行开始显示行号
head -n 4 file# 查看文件的前4行
tail -n 8 file# 查看文件的最后8行
tail -n +500 file# 从第500行开始显示，即只显示500行以后的
cat file | head -n 200 | tail -n +100# 显示100-300行的
cat file | tail -n +200 | head -n 100# 从第200行开始，显示100行（即200-299行）

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命令11：ps

ps命令是用来查看系统中的进程所在的状态

ps -a：查看所有的进程（包含其他用户的进程）

[root@bunian ~]# ps -a
PID TTYTIME CMD
579 pts/000:00:00 ps

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ps -u：查看用户及其他信息

[root@bunian ~]# ps -u
USER PID %CPU %MEMVSZ RSS TTYSTAT START TIME COMMAND
root 6250.00.0 1554481832 pts/0R+ 01:25 0:00 ps -u
root13990.00.0 110208 664 tty1 Ss+Dec01 0:00 /sbin/agetty --noclear tty1 linux
root14040.00.0 110208 640 ttyS0Ss+Dec01 0:00 /sbin/agetty --keep-baud 115200,38400,96
root 188280.00.0 1167283268 pts/0Ss Dec19 0:00 -bash

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ps -x：显示没有控制终端的进程

[root@bunian ~]# ps -x
PID TTYSTAT TIME COMMAND
1 ?Ss 1:36 /usr/lib/systemd/systemd --switched-root --system --deserialize 22
2 ?S0:00 [kthreadd]
4 ?S< 0:00 [kworker/0:0H]
6 ?S0:27 [ksoftirqd/0]
7 ?S0:08 [migration/0]
8 ?S0:00 [rcu_bh]
9 ?S 17:06 [rcu_sched]
 10 ?S< 0:00 [lru-add-drain]
 ......此处省略

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Linux系统中进程的5种常见状态

R：运行，进程正在运行或者在队列中等待

S：中断，进程处于休眠状态中。当接受到某个条件后，即可脱离该状态

D：不可中断，在这种状态下即使kill命令也无法将其中断

Z：僵死，进程已经终止，但是进程描述符依然存在。若父进程调用wait()系统函数后将进程释放

T：停止，进行收到停止信号后停止运行

命令12：top

top命令是用来动态地监控进程活动或者系统负载等信息的，它的功能可以看做是Windows系统中的“Windows任务管理器”。

查询进程的端口号：

netstat -tunlp | grep 端口号

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命令13：pidof

该命令是用来查询某个指定的服务进程的pid值

pidof sshd  # 查看sshd服务的进程pid值

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命令14：kill、killall

kill用于终止某个指定pid号的服务进程

kill 18828  # 杀死pid为18828的服务

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killall用来终止某个指定名称的服务所对应的全部进程，参数为进程名称

pidof httpd#查询httpd服务的全部进程
killall httpd # 终止http服务的全部进程

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命令15：ifconfig

ifconfig命令主要是用来获取网卡配置和系统的网络状态等信息，主要信息为：

网卡名称
inet参数后面的IP地址
MAC地址
RX、TX的接收和发送数据等信息

eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>mtu 1500
inet 10.0.8.2netmask 255.255.252.0broadcast 10.0.11.255
inet6 fe80::5054:ff:fe95:2cdfprefixlen 64scopeid 0x20<link>
ether 52:54:00:95:2c:dftxqueuelen 1000(Ethernet)
RX packets 48350308bytes 13922587280 (12.9 GiB)
RX errors 0dropped 0overruns 0frame 0
TX packets 50364002bytes 30975667765 (28.8 GiB)
TX errors 0dropped 0 overruns 0carrier 0collisions 0

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命令16：history

history命令主要是用来查看我们敲过的历史命令。

history# 查看全部历史命令
history 10# 查看最近的10条命令

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history可以与grep、tail配合使用进行条件过滤来查找我们需要的命令：

history | grep dnf# 和dnf相关的命令
history | tail -n 3 # 末尾3条命令

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清除历史命令：

history-d 50# 清除第100条
history -c# 全部清除掉

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