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Text editing with sed

sed, short for Stream Editor, is a Unix utility that parses and transforms text, often in a single line of code.

Use Cases

Find and replace

Replaces the first occurrence of "apple" with "orange" on each line.

sed 's/apple/orange/g' file.txt

Adds the g flag to replace all instances per line.

Delete a Line

Deletes the 3rd line

sed '3d' file.txt

Deletes any line containing the word "error".

sed '/error/d' file.txt

Insert or Append

Inserts a line before line 3

sed '3i\New line above line 3' file.txt

Appends a line after line 3

sed '3a\New line below line 3' file.txt

Prints only line 5. The -n flag suppresses automatic output.

sed -n '5p' file.txt

Prints lines 2 through 4

sed -n '2,4p' file.txt