Common Linux shell commands (2)

6. user and group related commands 1. groupadd command function: add groupaddtest1 & nbsp; add test1 group groupadd-g1111test2 & nbsp; add test2 group, group id 11112, useradd command function: add user useradduser1 & nbs 6. user and group commands

1. groupadd command

Function: Adds a group.

Groupadd test1 add test1 Group

Groupadd-g 1111 test2 add test2 group with id 1111

2. useradd command

Function: add a user

Useradd user1 add user user1, home is/home/user1, group is user1

Useradd-g test1-m-d/home/test1 test1 add user test1, home is/home/test1, group is test1

User list: displays the list of logged-in users

3. passwd command

Function: change the user password.

Passwd user1: change the password of user1.

Passwd-d root: delete the password of the root user

4. userdel command

Function: delete a user.

Userdel user1 delete user1 user

5. chown command

Function: change the owner of a file or directory.

Chown user1/dir: Set the/dir directory to all

Chown-R user1.user1/dir: set all the files and directories in the/dir directory to user1 and set the group to user1. -R recursion to each file and directory below

6. chgrp command

Function: changes all groups of files or directories.

Chgrp user1/dir set the/dir directory to all

7. chmod command

Function: change user permissions.

Chmod a + x file sets the file to executable, and the script file must be set in this way. Otherwise, it must be executed using bash file.

Chmod 666 file: Set the file to read/write.

Chmod 750 file: sets the file as the full permission of the owner. the file can be read and executed in the same group. other files have no permissions.

8. id command

Function: displays user information, including uid and gid.

# Id zhoulj

Uid = 500 (zhoulj) gid = 500 (zhoulj) groups = 500 (zhoulj)

9. finger command

Function: displays information for use.

Note: this command is not available in debian.

# Finger zhoulj

Login: zhoulj Name:

Directory:/home/zhoulj Shell:/bin/bash

On since Sun May 21 07:59 (CST) on pts/0 from 192.168.1.4

No mail.

No Plan.

VII. compression commands

1. gzip commands

Function: compress the file in gz format.

Note: the generated file overwrites the source file.

Gzip-v Compress the file and display the progress

-D Extract

Gnuzip-f Extract

For example:

# Gzip a. sh

# Ll

-Rwxr-xr-x 1 root 71 Aug 17 21:08 a.sh.gz

# Gzip-d a.sh.gz

# Ll

-Rwxr-xr-x 1 root 48 December 18 21:08 a. sh

2. zip commands

Function: zip commands for compression and decompression

Zip

Unzip

For example:

# Zip a.sh.zip a. sh

Adding: a. sh (stored 0%)

# Ll

-Rw-r? R? 1 root 188 May 21 10:37 a.sh.zip

# Unzip a.sh.zip

Archive: a.sh.zip

Replace a. sh? [Y] es, [n] o, [A] ll, [N] one, [r] ename: r

New name: a1.sh

Extracting: a1.sh

# Ll

-Rwxr-xr-x 1 root 48 December 18 21:08 a1.sh3 and bzip2 commands

Function: bzip2 compression command,

Note: the generated file overwrites the source file.

Bzip2

Bunzip2

For example:

# Bzip2 a. sh

# Ll

-Rwxr-xr-x 1 root 85 December 18 21:08 a.sh.bz2

# Bunzip2 a.sh.bz2

# Ll

-Rwxr-xr-x 1 root 48 December 18 21:08 a. sh

4. tar command

Function: archive, compress, etc. it is important and will be used frequently.

-Cvf Compressing files or directories

-Xvf Decompress a file or directory

-Zcvf Compressed file or, in the format of tar.gz

-Zxvf Uncompressed file or, in the format of tar.gz

-Zcvf Compressed file or, in the format of tgz

-Zxvf Decompress the file or, in the format of tgz

Example:

# Tar cvf abc.tar *. sh

# Tar xvf abc.tar

# Tar czvf abc.tar.gz *. sh

# Ll

-Rw-r? R? 1 root 20480 May 21 10:50 abc.tar

-Rw-r? R? 1 root 1223 May 21 10:53 abc.tar.gz

# Tar xzvf abc.tar.gz

8. network-related commands

1. ifconfig command

Function: displays the information for modifying the NIC.

Ifconfig displays network information

Ifconfig eth0 displays eth0 network information

Modify network information:

Ifconfig eth0 192.168.1.1 netmask 255.255.255.0 set the IP address 192.168.1.1 of Nic 1, mask 255.255.255.0

Ifconfig eth0: 1 192.168.1.2 bind the second address of network card 1 to 192.168.1.2

Ifconfig eth0: x 192.168.1.n the nth address of network card 1 bound to 192.168.1.n

For example:

# Ifconfig eth0: 1 192.168.1.11

# Ifconfig

Eth0 Link encap: Ethernet HWaddr 00: 0C: 29: 06: 9C: 24

Inet addr: 192.168.1.5 Bcast: 192.168.1.255 Mask: 255.255.255.0

Up broadcast running multicast mtu: 1500 Metric: 1

RX packets: 4220 errors: 0 dropped: 0 overruns: 0 frame: 0

TX packets: 3586 errors: 0 dropped: 0 overruns: 0 carrier: 0

Collisions: 0 fig: 1000

RX bytes: 342493 (334.4 Kb) TX bytes: 469020 (458.0 Kb)

Interrupt: 9 Base address: 0 ×1400

Eth0: 1 Link encap: Ethernet HWaddr 00: 0C: 29: 06: 9C: 24

Inet addr: 192.168.1.11 Bcast: 192.168.1.255 Mask: 255.255.255.0

Up broadcast running multicast mtu: 1500 Metric: 1

Interrupt: 9 Base address: 0 ×1400

2. route command

Function: displays the current html "target = _ blank> route settings

The current route settings are displayed on the route page.

Route add-net 10.0.0.0 netmask route 255.0.0 gw 192.168.1.254 add static route

Route del-net 10.0.0.0 netmask route 255.0.0 gw 192.168.1.254 add a static route

Route add default gw 192.168.1.1 metric1 set 192.168.1.1 as the default route

Route del default deletes the default route

Example:

# Route add-net 10.0.0.0 netmask 255.255.0.0 gw 192.168.1.254

# Netstat-nr

Kernel IP routing table

Destination Gateway Genmask Flags MSS Window irtt Iface

192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0

10.0.0.0 192.168.1.254 & nb