Processing strings in Shell

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Abstract: string processing in Shell
Processing strings
Including: intercept, connection, match, replace, flip ......
One day accumulated!
String processing:
1. truncate
Method 1:
Echo $ A | awk '{print substr (, 1, 8 )}'
Substr is a subfunction in the awk. It intercepts the first parameter. It starts from the first character and truncates 8 characters in total. If not, it is added to the second character.
Method 2
Echo $ A | cut-b2-8
Cut: process the standard input string
Cut-BN-M: in bytes, starting from n Bytes, take M
Cut-BN, M: the unit is byte. The N and M bytes are intercepted.
Cut-B-n, m: in bytes, intercept 1-N, and the M
-C: the unit is charactor.
-D: Specifies the delimiter. The default Delimiter is tab.
-S: Enable standard input without delimeter
Cut-F1: intercepts 1st Fields
Method 3
A = 123456
Echo $
Method 4
Use sed to extract the last two digits of a string
Echo $ test | SED's // (. */)/(../) $ //'
Truncates the first two digits of a string.
Echo $ test | SED's/^ /(../)/(.*/)//'
2. Comparison
There seems to be nothing to compare.
3. Connection
$ A $ B
Or
$ String
4. Flip
Method 1:
Run the rev command
Method 2:
Script implementation
#! /Usr/bin/awk-F
######################################## ########################
# Description: duplicate Rev in awk
######################################## ########################
{
Revline = ""
For (I = 1; I <= length; I ++)
{
Revline = substr (, I, 1) revline
}
}
End {print revline}
5. Match
Grep
Egrep
Fgrep
6. Sort
7. Replace
Bash:
% X = abcdabcd
% Echo $ # Replace only one
Bbcdabcd
% Echo $ # Replace all
Bbcdbbcd
SH:
??
How to replace/
Use SED
Replace all matches
Echo $ test | SED's/XX/yy'
Replace a single match
??
8. Obtain the length of the string:
Bash
$
Or
Expr "$ Var ":'.*'
9. determines whether the string is a number.
10 to obtain the number of repetitions of a character in the string.
Echo $ A | TR "X" "/N" | WC-l
The result is subtracted from 1.
Or
Echo $ A | awk-F "X" '{print NF-1 }'
11. Obtain the number of repetitions of a string in the string.
12. replace all strings in a batch of Files
For I in file_list
Do
VI $ I <-!
: G/xxxx/S // xxxx/g
: WQ
!
Done
13. How to insert one character between every two characters in a string
Use SED
Echo $ test | SED's/../& [insert char]/G'