You may not know the shell

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.

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-d@1234567890
  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 user@server  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 User@host 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.

Finally, the shell's Words of wisdom: (Chenhao Note: The mug below is very good ah, 404null.com very interesting)

You may not know the shell