The shell is also called the command line interface, which is the interface between the user and the computer under the *nix operating system. The word shell refers to the program in the operating system that provides access to the kernel service.
This article introduces some of the shell's non-well-known, but useful, and interesting knowledge, and the right to taste the dessert after the shell staple.
Science
A few facts that you may not know about first:
- The shell was almost born with the Unix operating system, and the first Unix shell was Ken Thompson (Ken Thompson), which was rewritten as a model in the shell of the Multics for 1971 years and named Thompson Sh. Even the later-popular bash (a variant of the shell) is actually older than all of the current Linux kernel, and on Linux systems there are shells and kernel.
- Most of the current *nix and MacOS os default shells are Bash,bash created by Brian Fox in 1987, full name Bourne Again Shell (bash).
- You may have heard of Bourne Shell (SH), Korn Shell (ksh), C shell (including CSH and tcsh) in addition to bash, but do you know that there are about 50 different kinds of shells on the planet? To know them, please refer to http://www.freebsd.org/ports/shells.html.
- Each month Tiobe a programming language ranking to show the popularity of various languages. The ranking index combines the number of engineers who use the language worldwide, the number of courses taught, and the number of third-party vendors. As of November 2012, the Tiobe published in the programming language leaderboard, the Bash index is 0.56% ranked 22. If you count the awk 0.21% and Tcl 0.146%, it will probably rank 14. Note that this does not include Bash's homologous siblings csh, ksh, etc., counting them, the shell family is expected to close to the top ten. It is worth mentioning that the shell has always been ranked stable, unlike some "nouveau riche" language, such as objective-c, these languages are popular entirely because of the rise of the current Apple department, but this craze is likely to come faster.
The world's largest source code warehouse GitHub, the number of shell-related projects accounted for 8%, among the top 5 and Java equivalent, visible in the actual combat project, the shell is Baodaobulao. Picture source, see here
A few powerful commands
Share some shell usages and scripts that you may not know about, simple & powerful!
Before reading the following sections, it is strongly recommended that the reader open a shell experiment that is not da Lu Huo in the shell textbook:)
!$
!$是一个特殊的环境变量，它代表了上一个命令的最后一个字符串。如：你可能会这样：
$mkdir mydir
$mv mydir yourdir
$cd yourdir
可以改成：
$mkdir mydir
$mv !$ yourdir
$cd !$
sudo !!
Executes the previous command as root.
Examples of scenarios: for example apt-get , when installing a package in Ubuntu, you need root, and we often forget to add it in front of you apt-get sudo . Each time you have to add sudo and re-type this line of command, it is very convenient to use the sudo !! finished.
(Chenhao Note: Under the shell, sometimes you will enter a very long command, you can use!XXX to repeat the last command, for example, you have previously entered, Vi/where/the/file/is, the next time you can use the!vi to the last time the VI command. ）
cd –
Go back to the previous directory.
Scenario Example: The current directory is /home/a , with the cd ../b switch to /home/b . You can cd – /home/a switch between and fro conveniently by repeatedly executing commands /home/b .
(Chenhao Note: cd ~ is to go back to their home directory, CD ~user, is to enter a user's home directory)
- ' ALT +. ' or ' <ESC>. '
Jechin ALT +. or esc+. You can repeat the arguments for the last command line.
^old^new
Replaces a partial string in the previous command.
Scene: echo "wanderful" , actually want to output echo "wonderful" . Just the right amount of time, a lot of help with the misspelling of ^a^o a long command. (Chenhao Note: !!:gs/old/newcan also be used)
- Du-s * | Sort-n | Tail
Lists the largest 10 files in the current directory.
- : w!sudo Tee%
Save a file in vi that only the root can write
- Date [email protected]
Time cut-off time
- > file.txt
Create an empty file that is shorter than touch.
- MTR coolshell.cn
The MTR command is better than traceroute.
- Add a space before the command line, and the command will not enter the history.
- echo "Ls-l" | At midnight
Run a command at a certain time.
- Curl-u user:pass-d status= "Tweeting from the shell" Http://twitter.com/statuses/update.xml
Command-line way to update Twitter.
- Curl-u username–silent "Https://mail.google.com/mail/feed/atom" | Perl-ne ' print ' \ t ' if/<name>/; Print "$2\n" if/< (Title|name) > (. *) <\/\1>/; '
Check your Gmail unread messages
- PS aux | Sort-nk +4 | Tail
List the first 10 most memory-consuming processes
man ascii
Displays the ASCII code table.
Scenario: Do I need Google to forget the ASCII code table? Especially in the celestial network so "smooth" situation, it is more trouble in GWF more application of a rule, directly with the local man ascii bar.
ctrl-x e
Quickly launch your default editor (set by variable $editor).
netstat –tlnp
Lists the port numbers that the native process listens on. (Chenhao Note: Netstat-anop can show the process listening on this port number)
tail -f /path/to/file.log | sed ‘/^Finished: SUCCESS$/ q‘
Exit tail when Finished:success appears in File.log, this command is used to monitor and filter log for a record in real time.
ssh [email protected] bash < /path/to/local/script.sh
Run a script on the remote machine. The biggest benefit of this command is that you don't have to copy the script to the remote machine.
- SSH [email protected] cat/path/to/remotefile | Diff/path/to/localfile-
Compare a remote file with a local file
- NET RPC shutdown-i ipaddressofwindowspc-u Username%password
Remotely shut down a Windows machine
screen -d -m -S some_name ping my_router
The background runs a program that does not terminate and can view its status at any time. The -d -m parameters start "Detach" mode, -S specifying the identity of a session. You can -R re-mount the session of an identity by command. Please refer to screen usage for more details man screen .
wget --random-wait -r -p -e robots=off -U mozilla http://www.example.com
Download the entire www.example.com website. (Note: Not too much, most sites have anti-crawling features:))
curl ifconfig.me
When your machine is in the net, you can use this command to view the IP of the external network.
- Convert input.png-gravity northwest-background transparent-extent 720x200 output.png
Change the size of a piece
lsof –i
View the active status of a native network service in real time.
- Vim Scp://[email Protected]//path/to/somefile
Vim a remote file
python -m SimpleHTTPServer
One sentence to implement an HTTP service, the current directory is set to the HTTP service directory, you can http://localhost:8000 access this is perhaps the most simple HTTP server on the planet implementation.
history | awk ‘{CMD[$2]++;count++;} END { for (a in CMD )print CMD[a] " " CMD[a]/count*100 "% " a }‘ | grep -v "./" | column -c3 -s " " -t | sort -nr | nl | head -n10
(Chenhao Note: A bit complicated, History|awk ' {print $} ' |awk ' BEGIN {fs= ' | '} {print "} ' |sort|uniq-c|sort-rn|head-10)
This line of script can output your most commonly used 10 commands, so you can even gain insight into what kind of programmer you are.
- Tr-c "[:d igit:]" "" </dev/urandom | DD cbs= $COLUMNS Conv=unblock | Grep_color= "1;32″grep–color" [^] "
Want to see Marix's screen effect? (not very similar, but also very cool!)
Do you know the code? It doesn't matter, learn the *nix shell script, recommend the Linux command line and Shell script programming encyclopedia.
Transferred from: http://coolshell.cn/articles/8619.html
You may not know the shell
