Common Linux Management Commands (Part 2)

6. touch create file command

The touch command is used to create a new blank file

• Command format: touch [-option] filename

#Create an empty file in the current directory
[root@localhost ~]# touch hello
[root@localhost ~]# ls
​
#Create multiple files at the same time in the current path
[root@localhost ~]# touch t1 t2 t3 t4
[root@localhost ~]# ls
​
#Create multiple files at the same time in the specified path
[root@localhost ~]# touch /opt/test1 /opt/test2 /opt/test3
[root@localhost ~]# ls /opt
rh  student  test1  test2  test3  xx
​
#If a directory with the same name exists, it cannot be created
[root@localhost ~]# mkdir test
mkdir: cannot create directory 'test': file already exists
​
#If there is a file with the same name, the touch command will not prompt, but the original file will not be overwritten
[root@localhost ~]# touch t1
​
#For directories, when there is only a single directory, "/" is optional
[root@localhost ~]# ls /opt/
rh  student  test1  test2  test3  xx
[root@localhost ~]# ls /opt
rh  student  test1  test2  test3  xx
​
#For a directory, when viewing the contents of the directory, there must be "/"
[root@localhost ~]# ls /opt/xx
and
​
#For files, there must be no "/" behind
[root@localhost ~]# ls /opt/test1
/opt/test1
[root@localhost ~]# ls /opt/test1/
ls: cannot access /opt/test1/: not a directory

7. cp copy command

cp (full spelling in English: copy file) is used to copy files or directories, and the cp command can also modify the directory or file name when copying

• Command format: cp [-option] source file or directory target directory

• Common options:

  • -p Keep the source file attributes unchanged (such as: modification time, affiliation, permissions)

  • -r copy directory (including all subdirectories and files under this directory)

• Use .with the cp command to perform copying ( .always indicate the current path)

#Copy the current directory file to the /opt directory (relative path copy)
[root@localhost ~]# cp t1 /opt/
[root@localhost ~]# ls /opt
rh  student  t1  test1  test2  test3  xx
​
#Copy files to /opt directory (absolute path copy)
[root@localhost ~]# cp /root/t2 /opt
[root@localhost ~]# ls /opt
rh  student  t1  t2  test1  test2  test3  xx
​
# Copy multiple files at the same time
[root@localhost ~]# cp t3 t4 /opt/
[root@localhost ~]# ls /opt
​
#Create a directory
[root@localhost ~]# mkdir abc
​
# Use -r to perform a copy of the directory
[root@localhost ~]# cp -r abc /opt
[root@localhost ~]# ls /opt
​
# Copy multiple directories at the same time
[root@localhost ~]# mkdir abc1 abc2 abc3
[root@localhost ~]# cp -r abc1 abc2 abc3 /opt
[root@localhost ~]# ls /opt
​
#Copy the hello file to /opt and rename it to hello.txt
[root@localhost ~]# cp hello /opt/hello.txt
[root@localhost ~]# ls /opt
​
#Copy the xxxx directory to /opt and rename it xxoo
[root@localhost ~]# mkdir xxxx
[root@localhost ~]# cp -r xxxx /opt/xxoo
[root@localhost ~]# ls /opt
​
#Use "." with the cp command to perform copying
[root@localhost ~]# cd /etc/sysconfig/network-scripts/
[root@localhost network-scripts]# pwd
/etc/sysconfig/network-scripts
​
[root@localhost network-scripts]# cp /root/t1 .
[root@localhost network-scripts]# ls
​
#Copy files with the same attributes
[root@localhost ~]# cp -p anaconda-ks.cfg /opt
cp: overwrite "/opt/anaconda-ks.cfg"? the y                         
[root@localhost ~]# ls -l /opt/anaconda-ks.cfg 
-rw-------. 1 root root 1800 Mar 13 17:34 /opt/anaconda-ks.cfg
​
#Compare the detailed attribute information of the above two files (last modification time)
[root@localhost ~]# ls -l anaconda-ks.cfg 
-rw-------. 1 root root 1800 Mar 13 17:34 anaconda-ks.cfg
​
#What do these two operations mean?
[root@localhost ~]# cp -r xxxx /mnt/oooo #copy and rename
[root@localhost ~]# cp -r xxxx /mnt/oooo #copy

8. mv cut command

mv (full spelling in English: move file) is used to move files or directories to other locations, and can also be used to modify directories or file names

• Command format: mv [-option] source file... target path

• Use .with the mv command

#Move the current path hello file to the /mnt directory
[root@localhost ~]# mv hello /mnt
[root@localhost ~]# ls /mnt
hello  home  oooo  test
​
# Move multiple files at the same time
[root@localhost ~]# mv t1 t2 t3 t4 /mnt
[root@localhost ~]# ls /mnt
hello  home  oooo  student1  t1  t2  t3  t4  test
​
#Move the files in the /opt directory to /mnt
root@localhost ~]# mv /opt/test1 /opt/test2 /opt/test3 /mnt/
[root@localhost ~]# ls /mnt
hello  home  oooo  student1  t1  t2  t3  t4  test  test1  test2  test3
​
# move directory
[root@localhost ~]# mv student1 /mnt
[root@localhost ~]# ls /mnt
hello  home  oooo  student1  test
​
#Move the file and rename it
[root@localhost ~]# mv hello.txt /media/hello
[root@localhost ~]# ls /media/
hello
​
#Move directory and rename
[root@localhost ~]# mv test /media/testxx
[root@localhost ~]# ls /media/
hello  testxx

9. cat view file content command

cat (English full spelling: concatenate) command is used to view the content of text files

• Command format: cat [options] filename

• Common options

  • -n #Display the file content in the form of line number when viewing the file

#View file content
[root@localhost ~]# cat anaconda-ks.cfg 
[root@localhost ~]# cat initial-setup-ks.cfg 
[root@localhost ~]# cat /etc/hosts
​
#View the content of the network card file, network card configuration file
[root@localhost ~]# cat /etc/sysconfig/network-scripts/ifcfg-ens32 
...
NAME="ens32" //Network card name
UUID="16085f4c-f690-4058-b29e-d55c73387026"
DEVICE="ens32"
ONBOOT="yes"
IPADDR="192.168.0.50" //Network card IP address
PREFIX="24" //subnet mask
GATEWAY="192.168.0.254" //Gateway
DNS1="114.114.114.114"    //DNS
​
#View the content of the current system user basic information file
[root@localhost ~]# cat /etc/passwd
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon : x : 2 : 2 : daemon : / sbin : / sbin / nlogin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
​
#View the content of the current system hostname configuration file
[root@localhost ~]# cat /etc/hostname
localhost.localdomain
​
#View the content of the current system version information file
[root@localhost ~]# cat /etc/centos-release 
CentOS Linux release 7.6.1810 (Core) 
​
#View the content of the current system boot configuration file automatically
[root@localhost ~]# cat /etc/fstab
​
#View the content of the basic information file of the system group
[root@localhost ~]# cat /etc/group
​
#Use "-n" to display the file content in the form of line numbers
[root@localhost ~]# cat -n /etc/passwd
[root@localhost ~]# cat -n /etc/hostname
[root@localhost ~]# cat -n /etc/fstab
[root@localhost ~]# cat -n /etc/group
[root@localhost ~]# cat -n /etc/services 
​

10. less command

The less tool is a tool for displaying the output of files in pages, and is often used to view files with large content

• Command format: less [-option] file

• Common options:

  • -N #Display the file content in the form of line number

• skills:

  • Keyboard up and down keys to view line by line

  • pgdn : turn down one page (Fn + Down Arrow)

  • pgup : turn up one page (Fn + up key)

• /string: Search for the specified string (n searches from top to bottom, N searches from bottom to top)

  • G: jump directly to the last line of the file

  • gg: jump directly to the beginning of the file line

  • : 1000 #Accurate positioning to a certain line

  • q : quit

[root@localhost ~]# less -N /etc/services