Bird Book Shell learning Note (ii) shell-related expressions

Wildcard characters differ from regular expressions The wildcard is the syntax that bash native supports,A regular expression is a representation of a string, and regular expressions require supported tool support to
Language settings: Export lang=cgrep alias settings: grep--color=auto
Some of the advanced parameters of grep
grep [-A] [-b] ' search string ' filename///output before the K-line and after the M-line-A: The following can be added number, indicating the list of rows and after the N line-B: List the previous lines
Search for keywords If you use regular expressions in the middle, then the regular expression section needs to add []eg:grep ' [a-z]oooo ' filename
Match the beginning of ' ^string ' but ' [^s]string ' means exclude s This letter matches line end ' string$ ' eg: Exclude comment lines, and empty lines grep-v ' ^$ '/etc/profile | Grep-v-n ' ^[[:blank:]]*# '


SED usage

sed [-NEFR] [action] sed can be manipulated directly on the fileOptions and Parameters:-N: Use Quiet (silent) mode. In the usage of general sed, all data from STDIN is generally listed on the screen. However, if you add the-n parameter, only the line (or action) that is specially processed by SED is listed. -E: Directly in the command columnmode.The action editor of Sed;-F: Writes the action of SED directly into a file, and the-f filename can run the SED action in filename; the-r:sed action supports the syntax of the extended formal notation. (The default is the basic formal notation of French)-I: Directly modifies the contents of the read file instead of being output by the screen. Action Description: [N1[,n2]]functionn1, N2: Not necessarily exist, generally represents "select the number of lines of action", for example, if my action is required between 10 to 20 rows, then the "10,20[action behavior" function bottom The following: A: New, a can be followed by a string, and these strings will appear in a new line (the current next line) ~c: Replace, C can be followed by strings, these strings can replace the line between N1,N2! D: Delete, because it is deleted, so d usually do not take any knock; I: Insert, I can be followed by a string, and these strings will appear on a new line (the current line); P: Print, that is, print out a selected data. Normally p will run with parameter sed-n ~s: Replace, can be directly replaced by work! Usually this s action can be paired with formal notation! For example 1,20s/old/new/g is! 

EG:NL Regular.txt | Sed ' 2,5d '//delete second to fifth line, the action behind SED must be "extended"
NL Regular | Sed ' 2a add hello ' after the second line adds data
NL Regular | Sed ' 2,5c change 2 to 5 line content ' replaces the contents of 2-5 lines
NL Regular | Sed-n ' 2,5p ' selected lines print out

Find and replace sed ' s/string to be replaced/new string/g '
Cat. BASHRC | Sed ' s/#.*$//g ' | Sed ' s/^$//g ' |grep-n ' exp '//Delete comment lines and blank lines

Sed-i ' s/\.$/\!/g ' regular//modify file directly

Awk's handy data processing tool
Suitable for small data processing

awk ' condition type 1{action 1} condition type 2{action 2} ... ' filename

wildcard characters

Special Regular
Regular
expansion of the regular

Bird Book Shell learning Note (ii) shell-related expressions