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This article mainly introduces the linux system user management and grep regular expression example analysis, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let Xiaobian take you to understand.

User Management and grep regular expression in linux system

1. Copy / etc/skel directory to / home/tuser1, which requires that the affiliated groups and other users of / home/tuser1 and its internal files do not have any access rights.

[root@suywien ~] # cp-rpv / etc/skel/ / home/tuser1/'/etc/skel/'->'/ home/tuser1/''/etc/skel/.mozilla'->'/ home/tuser1/.mozilla''/etc/skel/.mozilla/extensions'->'/ home/tuser1/.mozilla/extensions''/etc/skel/.mozilla/plugins'->'/ home/tuser1/.mozilla/plugins''/etc/skel/.bash_logout' ->'/ home/tuser1/.bash_logout''/etc/skel/.bash_profile'->'/ home/tuser1/.bash_profile''/etc/skel/.bashrc'->'/ home/tuser1/.bashrc' [root@suywien ~] # useradd tuser-d / home/tuser1/useradd: warning: the home directory already exists.Not copying any file from skel directory into it. [root@suywien ~] # chmod-R go-rwx / home/tuser1/ [root@suywien ~] # ll-d / home/tuser1/drwx- 3 root root 74 Feb 12 03:04 / home/tuser1/

2. Edit the / etc/group file and add the group hadoop.

[root@suywien ~] # vim / etc/group [root@suywien ~] # tail-1 / etc/grouphadoop:x:1029

3. Manually edit the / etc/passwd file to add a new line and add the user hadoop. Its basic group ID is the id number of the hadoop group; its home directory is / home/hadoop.

[root@suywien ~] # vim / etc/passwd [root@suywien ~] # tail-1 / etc/passwdhadoop:x:1029:1029::/home/hodoop/:/bin/bash

4. Copy / etc/skel directory to / home/hadoop, which requires that the subordinate groups and other users who modify the hadoop directory do not have any access rights.

[root@suywien ~] # cp-fpv / etc/skel/ / home/hadoopcp: omitting directory'/ etc/skel/' [root@suywien ~] # cp-fpvR / etc/skel/ / home/hadoop'/etc/skel/'->'/ home/hadoop''/etc/skel/.mozilla'->'/ home/hadoop/.mozilla''/etc/skel/.mozilla/extensions'->'/ home/hadoop/.mozilla/extensions''/etc/skel/.mozilla / plugins'->'/ home/hadoop/.mozilla/plugins''/etc/skel/.bash_logout'->'/ home/hadoop/.bash_logout''/etc/skel/.bash_profile'->'/ home/hadoop/.bash_profile''/etc/skel/.bashrc'->'/ home/hadoop/.bashrc' [root@suywien ~] # chmod go-rwx / home/hadoop/ [root@suywien ~] # ls-ld / home/hadoop/drwx -3 root root 74 Feb 12 03:04 / home/hadoop/

5. Modify the / home/hadoop directory and all its internal files. The owner is hadoop, and the group is hadoop.

[root@suywien] # chown-R hadoop:hadoop / home/hadoop/ [root@suywien] # ll-al / home/hadoop/total 16drwx3 hadoop hadoop 74 Feb 12 03:04. Drwxr-xr-x. 10 root root 4096 Mar 25 10:14.-rw-r--r-- 1 hadoop hadoop 18 Nov 20 2015. Bash _ logout-rw-r--r-- 1 hadoop hadoop 193 Nov 20 2015. Bash _ profile-rw-r--r-- 1 hadoop hadoop 231 Nov 20 2015. Bashrcdrwxr-xr-x 4 hadoop hadoop 37 Feb 12 03:03 .Mozilla

6. Display lines in the / proc/meminfo file that begin with uppercase or lowercase S; in two ways

[root@suywien ~] # grep ^ [Stemags] / proc/meminfo SwapCached: 0 kB SwapTotal: 2097148 kB SwapFree: 2097148 kB Shmem: 9100 kB Slab: 89476 kB SReclaimable: 53176 kB SUnreclaim: 36300 kB [root@suywien ~] # grep-I "^ s" / proc/meminfo SwapCached: 0 kB SwapTotal: 2097148 kB SwapFree: 2097148 kB Shmem: 9100 kB

7. Show users whose default shell is not / sbin/nologin in the / etc/passwd file

[root@suywien ~] # grep\ / sbin\ / nologin$ / etc/passwdbin:x:1:1:bin:/bin:/sbin/nologindaemon:x:2:2:daemon:/sbin:/sbin/nologinadm:x:3:4:adm:/var/adm:/sbin/nologinlp:x:4:7:lp:/var/spool/lpd:/sbin/nologinmail:x:8:12:mail:/var/spool/mail:/sbin/nologin.

8. Display the user whose default shell is / bin/bash in the / etc/passwd file

[root@suywien ~] # grep\ / bin\ / bash / etc/passwdroot:x:0:0:root:/root:/bin/bashroo:x:1000:1000:root:/home/roo:/bin/bashgentoo:x:4001:4001::/home/gentoo:/bin/bashmageia:x:1100:1100::/home/linux:/bin/bashtuser:x:4003:4003::/home/tuser1/:/bin/bashhadoop:x:1029:1029::/home/hodoop/:/bin/bash

9. Find one or two digits in the / etc/passwd file

[root@suywien ~] # grep "\" / etc/passwdmail:x:8:12:mail:/var/spool/mail:/sbin/nologinoperator:x:11:0:operator:/root:/sbin/nologingames:x:12:100:games:/usr/games:/sbin/nologinftp:x:14:50:FTP User:/var/ftp:/sbin/nologin.

10. Display lines in / boot/grub/grub.conf that begin with at least one white space character

[root@suywien ~] # grep "^ [[: space:]]\ +" / boot/grub2/grub.cfg load_env set default= "${next_entry}" set next_entry= save_env next_entry set boot_once=true.

11. Display a line in the / etc/rc.d/rc.sysinit file that begins with #, followed by at least one white space character, followed by at least one non-white space character

[root@suywien ~] # grep "^ # [[: space:]]\ + [^ [: space:]]\ +" / etc/rc.d/rc.local # THIS FILE IS ADDED FOR COMPATIBILITY PURPOSES# It is highly advisable to create own systemd services or udev rules# to run scripts during boot instead of using this file.# In contrast to previous versions due to parallel execution during boot# this script will NOT be run after all other services.# Please note that you must run 'chmod + x / etc/rc.d/rc.local' to ensure# that this script will be executed during boot.

12. Type the line after 'LISTEN', or ending with a white space character in the execution result of the netstat-tan command

[root@suywien ~] # netstat-tan | grep "LISTEN [[: space:]] * $" tcp 0 0 192.168.122.1 LISTEN 53 0.0.0.0 * LISTEN tcp 00 0.0.0.0 22 0.0.0.0 * LISTEN tcp 0 0127.0.0.1 tan 631 0.0.0.0 * LISTEN tcp 0 0127.0.0.0.1 25 0.0.0.0 LISTEN tcp6 0 0: 22: * LISTEN tcp6 0 0:: 1 LISTEN tcp6 0 0:: 1:25: * LISTEN

13. Add users bash, testbash, basher, nologin (the shell of this user is / sbin/nologin), and then find out the information of the user whose user name is the same as the default shell on the current system.

[root@suywien ~] # useradd bash [root@suywien ~] # useradd basher [root@suywien ~] # useradd-s / sbin/nologin nologin [root@suywien ~] # grep-E "^ ([^:] +\ >). *\ 1 $" / etc/passwdsync:x:5:0:sync:/sbin:/bin/syncshutdown:x:6:0:shutdown:/sbin:/sbin/shutdownhalt:x:7:0:halt:/sbin:/sbin/haltbash:x:4004:4004:: / home/bash:/bin/bashnologin:x:4006:4006::/home/nologin:/sbin/nologin Thank you for reading this article carefully I hope the article "user Management of linux system and sample Analysis of grep regular expressions" shared by the editor will be helpful to you. At the same time, I hope you will support us and pay attention to the industry information channel. More related knowledge is waiting for you to learn!

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