comm

Select or reject lines common to two files. Both files must be sorted. More information: https://www.gnu.org/software/coreutils/comm.

• Produce three tab-separated columns: lines only in first file, lines only in second file and common lines:
  comm {{file1}} {{file2}}
• Print only lines common to both files:
  comm -12 {{file1}} {{file2}}
• Print only lines common to both files, reading one file from stdin:
  cat {{file1}} | comm -12 - {{file2}}
• Get lines only found in first file, saving the result to a third file:
  comm -23 {{file1}} {{file2}} > {{file1_only}}
• Print lines only found in second file, when the files aren't sorted:
  comm -13 <(sort {{file1}}) <(sort {{file2}})