Sed Study Notes

Statement:
These codes are only used to learn and understand the SED command.
It represents the only or optimal solution to the problem.

References
Expected: <sed&awk=>
I. Replacement

1. magic transformation (Y
Command
Use)

Code:

Sed 'y/ori_letter_list/target_letter_list/'filename

Code:

Cat filename 1234567890 2345678901 3456789012 4567890123

Test
Set
File 1
Change to

2 In the file
Change to B

...
0 in the file
Change to J

Code:

Sed 'y/1234567890/abcdefghij/'filename Abcdefghij Bcdefghija Cdefghijab Defghijabc

Note that the conversion relationship is converted according to the positions of the two lists. Y is a local command and the suffix flag/g is not allowed.

List1: 1234567890
List2: abcdefghij
Lower
Returns a transform opposite to the transform.

Code:

Sed 'y/0987654321/abcdefghij/'filename Jihgfedcba Ihgfedcbaj Hgfedcbaji Gfedcbajih

2. Replace the first match in each line

Code:

Sed's/regexpr/anyword/'filename Sed 'S/regexpr/anyword/1 'filename

Example:

Reference:

Cat filename 1234567890 2345678901 3456789012 4567890123 Sed's/5/5/'filename 1234 5 67890 2345 678901 34 v 6789012 45 67890123

3. replace N in each line (if there is
) Match

Code:

Sed "s/regexpr/anyword/$ {n}" filename Cat filename 111111111111111111 222222222222222222 333333333333333333 444444444444444444 Example Example Sed "s/4/4/8" filename 111111111111111111 222222222222222222 333333333333333333 4444444 4 4444444444

4. Replace all matches in each row

Code:

Cat filename 1234567890 2345678901 3456789012 4567890123

Code:

Example: Sed's/3/3/G' filename 12, 3, 4567890 2 3 45678901 3, 456789012, 456789012, and 3

Ii. row number processing

1.
Add a row number to the file

Code:

Sed = filename | sed 'n'; S // n /:/' Cat filename 111111111111111111 222222222222222222 333333333333333333 444444444444444444

Example

Code:

Sed = filename | sed 'n'; S // n/:/'filename' 1111111111111111 2: 2222222222222222 33333333333333333 4:444444444444444444

2. Only Add rows to the text line in the file
No.

Code:

Sed/./= A | sed '/./N; S // n /:/'

Example

Code:

Cat filename 111111111111111111 222222222222222222 333333333333333333 444444444444444444 Sed/./= A | sed '/./N; S // n/:/' filename 1111111111111111 3:222222222222222222 43333333333333333 6:4444444444444444

Iii. String flip

Code:

Sed '// n /! G; S // (./)/(. */n/)/&/2/1/; // D; S /.//'

Example

Code:

Echo 1234567890 | SED '// N /! G; S // (./)/(. */n/)/&/2/1/; // D; S /.//' 0987654321

Iv. Selective output

1. Print the odd number of lines in the document (output across rows)

Code:

Sed 'n'; D' Sed 'x; $! N; x' Sed-n'p; N' 1 3 5 7

2. Print an even number of rows (output through the same line)

Code:

Sed-n'n'; P' Sed '1d; n; D ;' 2 4 6 8

3. Delete duplicate rows in large quantities
Note that the pattern space file is too large)

Code:

Sed '$! N;/^/(. */)/n/1 $ /! P; D' # Use $! N beware of memory overflow

Example

Code:

Cat File 111111111111111111 222222222222222222 222222222222222222 333333333333333333 444444444444444444 444444444444444444 444444444444444444 444444444444444444 444444444444444444 Sed '$! N; /^/(. */)/N/1 $ /! P; D' filename 111111111111111111 222222222222222222 333333333333333333 444444444444444444

4. Merge upper and lower rows and separate them with spaces
Isolation

Code:

Sed '$! N; S // N //'

Example

Code:

Cat File 1234567890 0987654321 After the command is executed 1234567890 0987654321

5. Merge the rows ending with a slash (/) and separate them with spaces (concatenate and disconnect rows)

Code:

Sed-E: A-E '// $/N; S // N //; TA'

Example

Code:

Cat filename 1 111111111111111111/ 2 222222222222222222 3 333333333333333333/ 4 444444444444444444 Sed -E: A-E '// $/N; S // N //; TA' filename 1 111111111111111111 2 222222222222222222 3 333333333333333333 4 444444444444444444

6. Merge rows by keywords

If a row starts with =, It is merged into the previous row and replaced with = as a space.

Code:

Sed-E: A-E '$! N; S // n = //; TA '-e' p; D'

Example

Code:

Cat File 111111111111111111 222222222222222222 = 333333333333333333 444444444444444444 Sed-E: A-E '$! N; S // n = //; TA '-e' p; D' Filename 111111111111111111 222222222222222222 333333333333333333 444444444444444444

7. output the next row of matching rows

Code:

Sed-n'/regexpr/{n; P;} 'filename

Example

Code:

Cat filename 1 111111111111111111 2 222222222222222222 3 333333333333333333 4 444444444444444444 Sed -N'/^ 3/{n; P;} 'filename 4 444444444444444444

8. Display and output the row number matching the row
Matches upstream, downstream

Sed-n-e '/regexpr/{=; X; 1! P; G; $! N; P; D ;}'
-E h
Example

Code:

Cat filename 1 111111111111111111 2 222222222222222222 3 333333333333333333 4 444444444444444444 Sed -N-e '/^ 3/{=; X; 1! P; G; $! N; P; D;} '-E h filename 3 # Match the row number 2 222222222222222222 # previous line 3 333333333333333333 # matching rows 4 444444444444444444 # Next line

9. delete a flag area in the document
Keyword match line

Delete the line containing myword in the block from being to end in the document.

Code:

Sed '/^ begin/,/^ end/{/myword/d;}' filename

Reference:

Cat filename Myword Begin Myword Number! Myword Number! Myword Number! Myword Number! End Myword Number!

Test

Reference:

Myword Begin Number! Number! Number! Number! End Myword Number!

5. String Parsing

1. parse two substrings (the first two characters and the last nine characters) from the string)

Code:

Echo "welovechinaunix" | sed-e 'H; S //(.. /). * // 1/; X; S /. */(. /{9/}/) $ // 1/; X; G; S // N //' We chinaunix

2. Split the date string

Code:

Echo 20030922 | SED's // (.../)/(../)/1/2 /3/'| read year month day Echo $ year $ month $ day 2003 09 22