I use less to view the text output of a command that has sensitive information. Less is good for this as it uses an alternate screen and wipes it after use. I'd like the less session to quit after a short time, like say 5 minutes.
Is there any simple command line way to invoke less with piped text and have it quit automatically after say 5 minutes?
Assuming you have GNU coreutils, a somewhat simple approach is to replace less with timeout --foreground 600 less; printf '\033[?47h'; clear; printf '\033[?1049l'; stty cooked echo in such sensitive commands. The timeout command kills a process after a given duration, the --foreground switch allows less to use the TTY, and stty cooked echo fixes the terminal after killing less. In case killing less prevented the clear and exit of the alternate screen, the intervening commands do that.
The escape sequences used in the printf commands are appropriate for a DEC-compatible terminal (emulator) such as Xterm. Your specific terminal may use different sequences to accomplish this task.
A simple function:
tless () {
timeout --foreground 600 less "$@"
printf '\033[?47h' # Enter alternate screen
clear
printf '\033[?1049l' # Exit alternate screen and restore cursor
</dev/tty stty cooked echo # Use in a pipe requires specifying the TTY
}
can make for substantially less typing.
Thanks @meuh for pointing out that the original version might not clear or exit the alternate screen.
Edited to allow tless some-file. Further, this version has been tested on Linux and Solaris 11.
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