/tmp/demo2>cat three-os.pl #!/usr/bin/perl use strict; use warnings; open OUT,'>','unix.txt' or die "unix.txt: $!"; print OUT "line 1\x0Aline 2\x0Aline 3\x0A"; close OUT; open OUT,'>','oldmac.txt' or die "oldmac.txt: $!"; print OUT "line 1\x0Dline 2\x0Dline 3\x0D"; close OUT; open OUT,'>','windows.txt' or die "windows.txt: $!"; print OUT "line 1\x0D\x0Aline 2\x0D\x0Aline 3\x0D\x0A"; close OUT; exec "file *.txt" or die "exec failed: $!"; /tmp/demo2>perl three-os.pl oldmac.txt: ASCII text, with CR line terminators unix.txt: ASCII text windows.txt: ASCII text, with CRLF line terminators /tmp/demo2> #### /tmp/demo2>file *.txt oldmac.txt: ASCII text, with CR line terminators unix.txt: ASCII text, with CRLF line terminators windows.txt: ASCII text, with CRLF, CR line terminators /tmp/demo2>od -tx1 -c windows.txt 0000000 6c 69 6e 65 20 31 0d 0d 0a 6c 69 6e 65 20 32 0d l i n e 1 \r \r \n l i n e 2 \r 0000020 0d 0a 6c 69 6e 65 20 33 0d 0d 0a \r \n l i n e 3 \r \r \n 0000033 /tmp/demo2>