Text processing the-sed basic usage of the Three Musketeers

Text Processing Three musketeers:

Grep,egrep,fgrep: Text filter Sed:stream Editor: Stream editor, line awk: Text formatting tool, Report Builder

Sed [option] ... ' script '  [input-file]     script: Address delimitation Edit Command                [option]           -n: Does not output the contents of the mode space to the screen           -e: multi-point editing           -f /path/to/sed_script_file:           -r:regexp-extend: Supports the use of extended regular expressions            -i:--in-place: Directly edit the original document           address delimitation:           1, empty address, processing of the full text            2, single address:                #: Specify line                / pattern/: Each line that is matched by this pattern           3, address range                 #,#:                #,+#:                #,/pat1/                /pat1/,/pat2/          4, Stepping:                1~2: All odd lines                 2~2: All even lines       edit commands:           d: Delete the contents of the pattern space            p: Display content in the mode space           a append:a  \text: Append text "text" after line, support using \ nTo implement multiline append           i insert:i \text: Insert text "text" before the line, Support for multi-line insert           c \text with \ n: replace the matched line with the text specified here "text"           w /path/to/somefile: Save the pattern space to match the line to the specified file            r /path/to/somefile: Reads the contents of the specified file to the back of the line to which the current file is matched;           =: Print line number for the line to which the pattern is matched            !: Conditional Inversion                  Address delimitation! Edit Command                 sed   '/^#/!d '  /etc/fstab                sed   '/^#/d '  /etc/fstab     s///: Find and Replace, The delimiter can be specified by itself and is commonly used [email protected]@@,s## #等            Replacement Tags                 g: Global Substitution                 w /path/to/somefile: Saves the result of the replacement success to the specified file                 p: Display of rows that have been replaced successfully

Practice

1. Remove all white-space characters from the beginning of all lines in the/boot/grub/grub2.cfg file that begin with a blank character

2. Delete all white characters after # and # of all lines beginning with # in the/etc/fstab file

3. Output an absolute path to the SED command and take out its directory, which behaves like dirname

Analytical

[email protected] grub]# Cat grub.conf | Sed ' [Email protected]^[[:space:]]\[email protected]@g '

[Email protected] grub]# Cat/etc/fstab | Sed ' [Email protected]^#[[:space:]]*@@ '

Path name: [[email protected] grub]# echo "/var/log/messages/" | Sed ' [Email protected][^/]\+/\[email protected]@g '

Path name: [[email protected] grub]# echo "/va" | Sed-r ' [email protected] (. */) ([^/].*)/[email Protected]\[email protected] '

Base name: [[email protected] grub]# echo "/var/log/messages" | Sed-r ' [Email protected]*/([^/].*)/[email Protected]\[email protected] '

This article is from the "Homecoming" blog, make sure to keep this source http://sixijie123.blog.51cto.com/11880770/1885816

Text processing the-sed basic usage of the Three Musketeers