Shulou(Shulou.com)05/31 Report--

This article mainly introduces "what are the basic commands of Linux". In daily operation, I believe many people have doubts about the basic commands of Linux. The editor consulted all kinds of materials and sorted out simple and easy-to-use methods of operation. I hope it will be helpful for you to answer the questions of "what are the basic commands of Linux?" Next, please follow the editor to study!

1. Tar

Create a new tar file

$tar cvf archive_name.tar dirname/

Extract the tar file

$tar xvf archive_name.tar

View the tar file

$tar tvf archive_name.tar2. Grep

Look for strings in the file (case-insensitive)

$grep-I "the" demo_file

Output the line that matches successfully, and the three lines after that line

$grep-A 3-I "example" demo_text

Recursively query the file containing the specified string in a folder

$grep-r "ramesh" * 3. Find

Find the file with the specified file name (case-insensitive)

$find-iname "MyProgram.c"

Execute a command on the found file

$find-iname "MyProgram.c"-exec md5sum {}\

Find all empty files in the home directory

Find ~-empty4. Ssh

Log in to the remote host

$ssh-l jsmith remotehost.example.com

Debug ssh client

$ssh-v-l jsmith remotehost.example.com

Show ssh client version

$ssh-V5. Sed

When you copy a file from the Dos system to Unix/Linux, each line of the file ends with\ r\ n.sed can easily convert it to a file in Unix format, using the file at the end.

$sed's Universe. Filename.

Reverse the contents of the file and output

$sed-n'1g; h; p 'filename

Add a line number to a non-blank line

$sed'/. / = 'thegeekstuff.txt | sed' N; s /\ n / /'6. Awk

Delete duplicate lines

$awk'! ($0 in array) {array [$0]; print} 'temp

Print all lines in / etc/passwd that contain the same uid and gid

$awk-F':'$3 million 4' / etc/passwd

Print the fields of the specified part of the file

$awk'{print $2 million 5;} 'employee.txt7. Vim

Open the file and skip to line 10

$vim + 10 filename.txt

Open the file and skip to the first matching line

$vim + / search-term filename.txt

Open a file in read-only mode

$vim-R / etc/passwd8. Diff

Ignore the white space character when comparing

$diff-w name_list.txt name_list_new.txt9. Sort

Sort the contents of the file in ascending order

$sort names.txt

Sort the contents of the file in descending order

$sort-r names.txt

Sort the contents of / etc/passwd by the third field

$sort-t:-k 3n / etc/passwd | more10. Export

Output environment variables that match the string oracle

$export | grep ORCALEdeclare-x ORACLE_BASE= "/ u01/app/oracle" declare-x ORACLE_HOME= "/ u01/app/oracle/product/10.2.0" declare-x ORACLE_SID= "med" declare-x ORACLE_TERM= "xterm"

Set global environment variables

$export ORACLE_HOME=/u01/app/oracle/product/10.2.011. Xargs

Copy all picture files to an external drive

$ls * .jpg | xargs-N1-I cp {} / external-hard-drive/directory

Compress and package all jpd files in the system

$find /-name * .jpg-type f-print | xargs tar-cvzf images.tar.gz

Download all url pages listed in the file

$cat url-list.txt | xargs wget-c12. Ls

Displays the file size in an easy-to-read way (displayed as MB,GB...)

$ls-lh-rw-r- 1 ramesh team-dev 8.9m Jun 12 15:27 arch-linux.txt.gz

Output the file in the last modified time-rise sequence

$ls-ltr

Display the file type after the file name

$ls-F13. Pwd

Output current working directory

14. Cd

Cd-you can switch between two recent working directories using shopt-s cdspell to set up automatic spell checking of cd commands

15. Gzip

Create a * .gz zip file

$gzip test.txt

Extract the * .gz file

$gzip-d test.txt.gz

Show the ratio of compression

$gzip-l * .gz compressed uncompressed ratio uncompressed_name 23709 97975 75.8% asp-patch-rpms.txt16. Bzip2

Create a * .bz2 zip file

$bzip2 test.txt

Extract the * .bz2 file

Bzip2-d test.txt.bz217. Uzip

Extract the * .zip file

$unzip test.zip

View the contents of the * .zip file

Unzip-l jasper.zipArchive: jasper.zipLength Date Time Name--40995 11-30-98 23:50 META-INF/MANIFEST.MF32169 08-25-98 21:07 classes_15964 08-25-98 21:07 classes_names10542 08-25-98 21:07 classes_ncomp18. Shutdown

Shut down the system and shut down the computer immediately

$shutdown-h now

Turn off the phone in 10 minutes

$shutdown-h + 10

Restart

$shutdown-r now

Force a system check during restart

$shutdown-Fr now19. Ftp

The use of the ftp command and the sftp command is basically similar. Connect to the ftp server and download multiple files.

$ftp IP/hostnameftp > mget * .html

Display a list of files on the remote host

Ftp > mls *. Html-/ ftptest/features.html/ftptest/index.html/ftptest/othertools.html/ftptest/samplereport.html/ftptest/usage.html20. Crontab

View a user's crontab entry

$crontab-u john-l

Set up a scheduled task to be executed every ten minutes

* / 10 * / home/ramesh/check-disk-space21. Service

The service command is used to run System V init scripts, which are usually located in the / etc/init.d file. This command can run the scripts in this folder directly without adding a path.

View service status

$service ssh status

View all service statu

$service-status-all

Restart the service

$service ssh restart22. Ps

The ps command is used to display information about running processes. The ps command has many options, and only a few are listed here.

View all currently running processes

$ps-ef | more

Displays the currently running process in a tree structure, and the H option indicates the hierarchy of the display process

$ps-efH | more23. Free

This command is used to display the current memory usage of the system, including used memory, available memory, and swapped memory

By default, free outputs memory usage in bytes

$free total used free shared buffers cachedMem: 3566408 1580220 1986188 0 203988 902960 Mozilla + buffers/cache: 473272 3093136Swap: 4000176 04000176

If you want to output memory usage in other units, you need to add an option,-g: GB,-m, MB,-k, KB,-b, bytes.

$free-g total used free shared buffers cachedMem: 3 1 1 0 0 Muhammad + buffers/cache: 0 2Swap: 3 0 3

If you want to see a summary of all memory, use the-t option, which will add a summary line to the output

Ramesh@ramesh-laptop:~$ free-t total used free shared buffers cachedMem: 3566408 1592148 1974260 0 204260 912556 3091076Swap + buffers/cache: 475332 3091076Swap: 40001760 4000176Total: 7566584 1592148 597443624. Top

The top command displays the most resource-intensive processes in the current system (sorted by CPU by default). If you want to change the sorting method, you can click O (uppercase O) in the results list to display all the columns available for sorting, at which point you can select the columns you want to sort.

Current Sort Field: P for window 1:DefSelect sort field via field letter, type any other key to return a: PID = Process Id v: nDRT = Dirty Pages count d: UID = User Id y: WCHAN = Sleeping in Function e: USER = User Name z: Flags = Task Flags.

If you want to display only the processes of a specific user, you can use the-u option

$top-u oracle25. Df

Displays the disk usage of the file system. By default, df-k will output disk usage in bytes.

$df-kFilesystem 1K-blocks Used Available Use% Mounted on/dev/sda1 29530400 3233104 24797232 12% / / dev/sda2 120367992 50171596 64082060 44% / home

Use the-h option to display disk usage in a way that is more consistent with reading habits

$df-hFilesystem Size Used Avail Capacity iused ifree% iused Mounted on/dev/disk0s2 232Gi 84Gi 148Gi 37% 21998562 38864868 36% / devfs 187Ki 187Ki 0Bi 100% 648 0% / devmap-hosts 0Bi 0Bi 0Bi 100% 00 100% / netmap Auto_home 0Bi 0Bi 0Bi 100% / home/dev/disk0s4 466Gi 45Gi 421Gi 10% 112774 0% / Volumes/BOOTCAMP//app@izenesoft.cn/public 2.7Ti 1.3Ti 1.4Ti 48% 018446744073709551615.0% / Volumes/public

Use the-T option to display the file system type

$df-TFilesystem Type 1K-blocks Used Available Use% Mounted on/dev/sda1 ext4 29530400 3233120 24797216 12% / / dev/sda2 ext4 120367992 50171596 64082060 44% / home26. Kill

Kill is used to terminate a process. Usually we will first use ps-ef to find a process to get its process number, and then use the kill-9 process number to terminate the process. You can also use killall, pkill, and xkill to terminate the process.

$ps-ef | grep vimramesh 7243 7222 9 22:43 pts/2 00:00:00 vim$ kill-9 724327. Rm

Confirm before deleting the file

$rm-I filename.txt

It is useful to use the meta character of shell in the file name. Print the file name and confirm it before deleting the file

$rm-I file*

Recursively delete all files under the folder and delete the folder

$rm-r example28. Cp

Copy file 1 to file 2 and maintain the permissions, ownership, and timestamp of the file

$cp-p file1 file2

Copy file1 to file2, and prompt whether to overwrite if file2 exists

$cp-I file1 file229. Mv

Rename the file name file1 to file2, and prompt whether to overwrite if file2 exists

$mv-I file1 file2

Note that if you use the-f option, you will not be prompted

-v outputs the renaming process, which is convenient when the file name contains wildcards

$mv-v file1 file230. Cat

You can view the contents of more than one file at a time. The following command prints the contents of file1 first, then the contents of file2.

$cat file1 file2

The-n command can precede each line with a line number

$cat-n / etc/logrotate.conf/var/log/btmp {missingok3 monthly4 create 0660 root utmp5 rotate 16} 31. Mount

If you want to mount a file system, you need to create a directory first, and then mount the file system to this directory

# mkdir / u01# mount / dev/sdb1 / u01

You can also add it to fstab for automatic mount, so that whenever the system restarts, the file system will be loaded.

/ dev/sdb1 / u01 ext2 defaults 0 232. Chmod

Chmod is used to change the permissions of files and directories

Give all permissions to the owner and group of the specified file (including read, write, execute)

$chmod ug+rwx file.txt

Deletes all permissions belonging to the group of the specified file

$chmod g-rwx file.txt

Modify the permissions of the directory and recursively modify the permissions of all files and subdirectories under the directory

$chmod-R ug+rwx file.txt33. Chown

Chown is used to change file owners and groups

At the same time, change the owner of a file to oracle and the group to db.

$chown oracle:dba dbora.sh

Use the-R option to recursively modify the directory and the files under the directory

$chown-R oracle:dba / home/oracle34. Passwd

Passwd is used to change the password on the command line. Using this command will require you to enter the old password first, and then enter the new password.

$passwd

Superusers can use this command to change the passwords of other users. There is no need to enter the user's password at this time.

# passwd USERNAME

Passwd can also delete a user's password. Only root users can operate this command. After deleting the password, the user can log in to the system without entering the password.

# passwd-d USERNAME35. Mkdir

Create a directory called temp under the home directory

$mkdir ~ / temp

Use the-p option to create a directory that does not exist on the path

$mkdir-p dir1/dir2/dir3/dir4/36. Ifconfig

Ifconfig is used to view and configure the network interface of the Linux system

View all network interfaces and their status

$ifconfig-a

Use the up and down commands to start or stop an interface

$ifconfig eth0 up$ ifconfig eth0 down37. Uname

Uname can display some important system information, such as kernel name, hostname, kernel version number, processor type and so on.

$uname-aLinux john-laptop 2.6.32-24-generic # 41-Ubuntu SMP Thu Aug 19 01:12:52 UTC 2010 i686 GNU/Linux38. Whereis

You can use the whereis command when you don't know the location of a command. Use whereis to find the location of ls

$whereis lsls: / bin/ls / usr/share/man/man1/ls.1.gz / usr/share/man/man1p/ls.1p.gz

When you want to find the location of an executable program, but the program is not in the default directory of whereis, you can use the-B option and specify the directory as the parameter for this option. The following command looks for the lsmk command in the / tmp directory

$whereis-u-B / tmp-f lsmklsmk: / tmp/lsmk39. Whatis

Wathis displays the description of a command

$whatis lsls (1)-list directory contents$ whatis ifconfigifconfig (8)-configure a network interface40. Locate

Locate naming shows the path to a specified file (or set of files), which uses a database created by updatedb

The following command displays all files on the system that contain crontab strings

$locate crontab/etc/anacrontab/etc/crontab/usr/bin/crontab/usr/share/doc/cron/examples/crontab2english.pl.gz/usr/share/man/man1/crontab.1.gz/usr/share/man/man5/anacrontab.5.gz/usr/share/man/man5/crontab.5.gz/usr/share/vim/vim72/syntax/crontab.vim41. Man

Display the man page of a command

$man crontab

Some commands may have multiple man pages, with each man page corresponding to a command type

$man SECTION-NUMBER commandname

Man pages can generally be divided into eight command types

User command system calls c library function device and network interface file format game and screensaver environment, table, macro system administrator commands and background running commands for example, when we execute whatis crontab, you can see that crontab has two command types 1 and 5, so we can view the man page of command type 5 with the following command

$whatis crontabcrontab (1)-maintain crontab files for individual users (V3) crontab (5)-tables for driving cron$ man 5 crontab42. Tail

The tail command displays the last 10 lines of text of the file by default

$tail filename.txt

You can use the-n option to specify the number of rows to display

$tail-n N filename.txt

You can also use the-f option for real-time viewing, which waits after execution. If new lines are added to the end of the file, it will continue to output new lines, which is very useful when viewing logs. You can terminate the execution of the command through CTRL-C

$tail-f log-file43. Less

This name displays the contents of the file without loading the entire file, which is useful when viewing large log files

$less huge-log-file.log

When you open a file with the less command, the following two buttons will help you a lot. They are used to scroll forward and backward.

CTRL+F-forward one windowCTRL+B-backward one window44. Su

The su command is used to switch user accounts. Superusers can use this command to switch to any other user without entering a password

$su-USERNAME

Execute a command with another user name in the following example, the user john executes the ls command using the raj user name, and returns the john account after execution

[john@dev-server] $su-raj-c 'ls' [john@dev-server] $

Log in with the specified user and use the specified shell program instead of the default

$su-s' SHELLNAME' USERNAME45. Mysql

Mysql is probably the most widely used database on Linux, and even if you don't have mysql installed on your server, you can use the mysql client to connect to a remote mysql server

To connect to a remote database, a password is required

$mysql-u root-p-h 192.168.1.2

Connect to the local database

$mysql-u root-p

You can also enter the database password on the command line, just add the password after-p as an argument, and you can write it directly after p without adding a space

forty-six。 Yum

Install apache using yum

$yum install httpd

Update apache

$yum update httpd

Uninstall / remove apache

$yum remove httpd47. Rpm

Install apache using rpm

# rpm-ivh httpd-2.2.3-22.0.1.el5.i386.rpm

Update apache

# rpm-uvh httpd-2.2.3-22.0.1.el5.i386.rpm

Uninstall / remove apache

# rpm-ev httpd48. Ping

Ping one remote host, sending only 5 packets

$ping-c 5 gmail.com49. Date

Set system date

# date-s "01Compact 31Universe 23:59:53"

When you modify the system time, you need to synchronize the hardware time with the system time

# hwclock-systohc# hwclock-systohc-utc50. Wget

Download software, music and videos from the Internet using wget

$wget http://prdownloads.sourceforge.net/sourceforge/nagios/nagios-3.2.1.tar.gz

Download the file and save it with the specified file name

At this point, the study of "what are the basic commands of Linux" is over for $wget-O taglist.zip http://www.vim.org/scripts/download_script.php?src_id=7701. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.