Pipeline and redirection under Linux

Pipeline and redirection under Linux

1. System default settings:
   

   Standard input: stdout,0

   Standard output: stdin,1

   Standard error Output: stderr,2

2.I/O Redirect:

: Overwrite output

SET-C: Disallow redirection of existing file overrides

To force overwrite output redirection: Use >|

Set +c: Enables redirection of file overrides that already exist

>>: Append output

2>: standard error output

2>>: Standard error Append method

&>: Standard or error output to the same file

Example Description: ls/etc/&>/tmp/err.txt

>filename 2>&1: As with the &> function, the output of standard or error to the same file

Example Description: ls/etc/>/tmp/err.txt 2>&1

<: Input redirection

<<eof:eof to the end, you can write the concluding character arbitrarily

To illustrate:

650) this.width=650; "src=" Http://s3.51cto.com/wyfs02/M02/7E/E1/wKioL1cLr9yS_MgtAAC4PyEIlq8987.jpg "title=" Eof.jpg "alt=" Wkiol1clr9ys_mgtaac4pyeilq8987.jpg "/>

3. Pipeline: The output of the previous command, as input to the latter command

Format: Command 1 | Command 2 | Command 3 | ...

Tee: Copies a copy saved to the specified file, and then prints one copy of the output to the screen

3.1. Example: Remove the user name and UID from the/etc/passwd file, and display in descending order of the UID number;

cut-d:-f1,3,/etc/passwd | SORT-T:-k2-n-R

3.2. Example: Remove the user name and UID of the 6th user in the/etc/passwd file and the shell, display it to the screen and save it to the/tmp/pw.txt file

Cut-d:-f1,3,7/etc/passwd | Tee/tmp/pw.txt

3.3. Example: Append alias COPY=CP line to the current user's. bashrc file without using a text editor

echo "Alias COPY=CP" >> ~/.BASHRC

This article is from the "Xavier Willow" blog, please be sure to keep this source http://willow.blog.51cto.com/6574604/1762757

Pipeline and redirection under Linux