# Output lines that appear in only file1
comm -1 file1.txt file2.txt
#
# Output lines that appear in only file1
comm -2 file1.txt file2.txt
# Output lines that appear in both files
comm -3 file1.txt file2.txt
# Output lines that appear in only file1
comm -1 file1.txt file2.txt
#
# Output lines that appear in only file1
comm -2 file1.txt file2.txt
# Output lines that appear in both files
comm -3 file1.txt file2.txt