Shell basic Commands

The shell is known as the system administrator's choice for its stability, efficiency, and flexibility. The basic shell commands are described below, including directory switching, locating and viewing files, viewing user information, and more.

1. Shell Introduction

The shell is a program that provides a line-oriented, interoperable interface between the user and the operating system. The user enters a command at the command line and the shell running in the background converts the command into a script to the operating system.

2. Printing conventions

$: Indicates user input

#: Indicates that the command is being executed as root

3. Browse your hard drive

--  Enter the root directory (CD command) and view the directory structure under the root directory (ll command) csv-cbweb01-cbossweb%cd /directory: /csv-cbweb01-cbossweb%ll total usage  220drwxr-xr-x    2 root root   4096  5 month    5 2010 selinux/drwxr-xr-x    2 root root   4096   5 Moon   5 2010 mnt/drwx------    2 root root   16384  7 Month  30 2013 lost+found/drwxr-xr-x   13 root root    4096  7 Month  30 2013 usr/drwxr-xr-x    4 root  root   4096  7 Month  30 2013 srv/drwxr-xr-x   15  Root root   4096  7 Month  30 2013 var/drwxr-xr-x     3 root root   4096  7 Month  30 2013 opt/drwxr-xr-x     4 rOot root   4096  7 Month  31 2013 home/drwxr-xr-x   13  root root   4096  9 Month  10 2015 lib/drwxr-xr-x     8 root root  12288  9 Month  10 2015 lib64/drwxr-xr-x     2 root root   4096  9 Month  10 2015 bin/ Drwxr-xr-x    3 root root  12288  9 Month  10 2015  Sbin/drwxr-xr-x    4 root root   4096  9 Month  10  2015 boot/drwxr-xr-x    2 root root   4096  9 Month  11 2015 media/drwxr-xr-x   18 1000 1000   4096   9 Month  16 2015 Python-2.7.10/drwxr-xr-x   24 root root    4096 12 Month  21&nbsP;01:31&NBSP, .... /drwxr-xr-x   24 root root   4096 12 Month  21 01:31 ./ Dr-xr-xr-x  164 root root      0 12 Month  21 09:31  proc/drwxr-xr-x   12 root root      0 12 Month  21 09:31 sys/drwxr-xr-x   16 root root   4160 12 Month  21 09:32 DEV/DRWX------   22 root root   4096   2 Month  18 10:42 root/drwxr-xr-x    5 root root    4096  2 Month  18 11:05 app/drwxr-xr-x  107 root root   12288  2 Month  18 11:05 etc/drwxrwxrwt 1792 root root 102400   5 Month  27 12:30 tmp/csv-cbweb01-cbossweb%cd /homedirectory: / Homecsv-cbweb01-cbossweb%ll Total Dosage &NBSp;16drwxr-xr-x  5 bsm  users 4096  7 Month  30 2013 bsm/ Drwxr-xr-x  6 zjwg users 4096  7 Month  30 2013 zjwg/drwxr-xr-x   4 root root  4096  7 Month  31 2013 ./drwxr-xr-x 24  root root  4096 12 month  21 01:31  /csv-cbweb01-cbossweb%--  Automatic Completion with TAB tab

4. viewing directories and files

--Show current directory pwdcsv-cbweb01-cbossweb%cd/usr/local/bin/directory:/usr/local/bincsv-cbweb01-cbossweb%pwd/usr/local/ bin--Change System directory Cdcsv-cbweb01-cbossweb%cd/usr/local/bin/directory:/usr/local/bincsv-cbweb01-cbossweb%pwd/usr/local/ bincsv-cbweb01-cbossweb% CD. /directory:/usr/localcsv-cbweb01-cbossweb%pwd/usr/local--listing directory contents ls and ls-lcsv-cbweb01-cbossweb% lscsv-cbweb01-cbossweb%ls-l--viewing files cat|more[filename]--the cat command will display everything on the screen at once. So it's not often used--the more command displays the content on a page-by-page. SPACEBAR to page, enter to roll, Q to exit Csv-cbweb01-cbossweb%more fbst--read the beginning and end of the file--head used to display the beginning of the file specify the number of rows displayed with the-n parameter--tail is used to display the end of the file, Usage is the same as head

5. Better text reading tools: less

Less is much more similar, but more powerful. Less displays a colon at the bottom of the screen: waits for the user's input command. The space is page down and the B key is page up. Use "/" to find what you want, q to exit

6. Find File Contents: grep

Grep[options] Pattern[file ...] --To find the row grep un day that contains UN in the file day

7. Locate the file within the specified range: find

Find[option] [path ...] [expression]--  find the Zip command in the User/bin directory csv-cbweb01-cbossweb%cd /directory: /csv-cbweb01-cbossweb% find /usr/bin/                lib/               sbin/               [email protected]games/              lib64/              share/              X11R6/include/            local/             src/                x86_64-suse-linux/csv-cbweb01-cbossweb %find /usr/bin/ -name zip -ppath   perm   print   print0 printf prune  csv-cbweb01-cbossweb%find /usr/bin/ -name zip - The Print/usr/bin/zipcsv-cbweb01-cbossweb%--find command also enables you to specify the type of file and to locate the file type by using the type parameter.     -type -b fast device files     -c  character device files       -d  directory file           -f common file     -p Named pipes     l Symbolic Links

8. Quickly locate files

--View the path of all doc files locate *.doc

9. Find a specific program: Whereis

The Whereis command is primarily used to locate program files

Csv-cbweb01-cbossweb%whereis Findfind:/usr/bin/find/usr/bin/x11/find/usr/share/man/man1p/find.1p.gz/usr/share/ Man/man1/find.1.gz

10, user and version information view

--who Command View current system has those people logged in Csv-cbweb01-cbossweb%whocbossweb pts/0 2016-05-27 12:28 (10.73.141.8) cbossweb PTS/1 2016 -05-26 10:42 (10.73.141.43) cbossweb pts/4 2016-05-26 16:26 (10.73.141.43)--If you forget what you are logged into the system, use Whoamicsv-cbweb01-c Bossweb%whoami cbossweb--uname-a View version information for the current system csv-cbweb01-cbossweb%uname-alinux csv-cbweb01 3.0.101-63-default #1 SMP Tue June 16:02:31 UTC (4b89d0c) x86_64 x86_64 x86_64 Gnu/linuxcsv-cbweb01-cbossweb%uname-r3.0.101-63-default

11. Ask for help--man command

The man command provides easy access to a command's help information

Csv-cbweb01-cbossweb%man Findman: Find all matching hand albums * FIND (1) find (1p) man: What manual pages do you need? ...

12, get the command introduction--Whatis and apropos

The lengthy speeches in the man handbook are too wordy, and many times we just want to know what an order is, and use Whatis to see

Csv-cbweb01-cbossweb%whatis Findfind (1p)-Find Filesfind (1)-Search for files in a directory hi Erarchy

The opposite command is apropos, which can be reversed by using the command in the manual. For example, if a user wants to search for a file and cannot remember which command to use, they can ask for help apropos

apparmor.d           applydeltaiso         aptcsv-cbweb01-cbossweb%apropos searchanemotaxis  (6x)        - directional search on a plane.apropos  (1)            - search the manual page names  and descriptionsausearch  (8)          - a tool  to query audit daemon logsausearch-expression  (5)  - audit search  expression formatbadblocks  (8)         - search  a device for bad blocksbsearch  (3)            - binary search of a sorted arraybsearch  (3p)           - binary search a sorted tablebzgrep  (1)             - search possibly bzip2 compressed files  FOR A REGULAR&NBSP, ..... class::isa  (3pm)      - report the search path for  A class ' s isa treecpanplus::internals::search  (3pm)  -  (δ) find  (1)               - search for files  in a directory hierarchygetgrnam  (3p)          - search group database for a namegetgrnam_r  (3p)        - search group database for a namegetpwnam  (3p)          - search user database for a namegetpwnam_r  (3p)       - search user database for a  namegetpwuid  (3p)         - search user  database for a user idgetpwuid_r  (3p)       -  search user database for a user idgnome-search-tool  (1)  - the  GNOME Search Toolgrep  (1p)              - search a file for a patterngrepjar  (1)            - search files in a jar file for  a patternhcreate  (3p)          - manage  hash search tablehdestroy  (3p)         - manage  hash search table...--  can see that the apropos command lists the entries that contain "search", where the user can find the one they want. 

13. Summary

• The command line is the quintessential part of Linux. All system management operations can be done under the shell

• There are many different shells to choose from. Currently, the most widely used Linux is bash

• You can use command line completion and wildcard characters to improve the efficiency of using the shell

• The PWD command is used to display the current directory information

• cd command in the directory key switch, which is one of the most frequently used commands in Linux

• The LS command provides a number of options for users to view directory content

• Dir and VDir are simplified versions of the LS command

• Use the Cat command to view files (all file contents). More command to display a longer text file in pagination

• Use the head and tail commands to display a header and end of file,-N to specify how many rows are displayed

• The less command provides more advanced functionality for viewing files. The man command is to display the help book information by calling less.

• The tool for finding the contents of a file when grep is in process

• The find command can find a specific file on demand

• Locate command to quickly locate file locations

• Whereis command to find where a particular program is located

• Who view current system with those people logged in

• Uname for displaying current system information

• Whatis and Apropos commands to extract brief information from the man manual
  

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Shell basic Commands