[2019-08-12 17:45] Jesse Smith <jsm...@resonatingmedia.com> > >> I tried it and the "head", "cat" and "tail" commands mangle the lines > >> of the log file when escape sequences are not escaped. Output from > >> "less" is clean though and looks correct. > > Interesting. Can you please send text that shows this behaviour?
> Certainly. Attached is a file with the last 20 lines of the > /var/boot/log file on a test machine. When I view the log with "less" > the output looks normal. When I run the file through "head" "tail" or > "cat" the "[ ok" part of the message line appears at the beginning of > the text. This happens in both the text console and in a virtual > terminal window. Ah, everything is clear now. Log file contains following escape sequence: <ESC> [ 1 G It moves cursor to first column of terminal, so text after displaces text (timestamp) at beginning of line. On other hand, `less -R' do not interpret cursor movement sequences (quote from less(1)): For the purpose of keeping track of screen appearance, ANSI color escape sequences are assumed to not move the cursor. If you use `less -r', output will be same as with `head', but I expect `less' get confused on scrolling. Cursor movement control sequences are okay for presentation, but are very fragile to be stored and manipulated in any way. I already filed bug to src:lsb to avoid control sequences more complex than coloring. -- Note, that I send and fetch email in batch, once in a few days. Please, mention in body of your reply when you add or remove recepients.