Sed #

sed is a stream editor. It can perform basic text transformations on an input stream (a file or input from a pipeline).

Common Sed Commands #

• Substitute (s): Replaces occurrences of a pattern with another string.

  sed 's/old_string/new_string/' filename # Replaces the first occurrence on each line
  sed 's/old_string/new_string/g' filename # Replaces all occurrences on each line
  sed 's/old_string/new_string/gi' filename # Replaces all occurrences case-insensitively
  sed -i 's/old_string/new_string/g' filename # In-place replacement
  

• Delete (d): Deletes lines that match a pattern.

  sed '/pattern/d' filename # Deletes lines containing 'pattern'
  sed '1d' filename # Deletes the first line
  sed '1,5d' filename # Deletes lines from 1 to 5
  sed '$d' filename # Deletes the last line
  

• Print (p): Prints lines that match a pattern.

  sed -n '/pattern/p' filename # Prints only lines containing 'pattern'
  sed -n '1,5p' filename # Prints lines from 1 to 5
  

  The -n option suppresses the default output, so only the explicitly printed lines are shown.

• Insert (i): Inserts text before a line.

  sed '1i\
  This is a new line inserted at the beginning.' filename
  

• Append (a): Appends text after a line.

  sed '$a\
  This is a new line appended at the end.' filename
  

• Transform (y): Transforms characters.

  sed 'y/abc/ABC/' filename # Transforms 'a' to 'A', 'b' to 'B', and 'c' to 'C'
  

Complex Sed Commands #

• Removes colors.

  sed -r "s/\x1B\[([0-9]{1,3}(;[0-9]{1,2};?)?)?[mGK]//g" filename