Whenever I use grep, and I pipe it to an other program, the --color option is not respected. I know I could use --color=always, but It also comes up with some other commands that I would like to get the exact output of that command as the output I would get if I was in a tty.
So my question is, is it possible to trick a command into thinking that the command is run inside a tty ?
For example, running
grep --color word file # Outputs some colors
grep --color word file | cat # Doesn't output any colors
I'd like to be able to write something like :
IS_TTY=TRUE grep --color word file | cat # Outputs some colors
This question seems to have a tool that might do what I want :empty - run processes and applications under pseudo-terminal (PTY), but from what I could read in the docs, I'm not sure it can help for my problem
There are a number of options, as outlined by several other Stack Overflow answers (see Caarlos's comment). I'll summarize them here though:
Use script + printf, requires no extra dependencies:
0<&- script -qefc "ls --color=auto" /dev/null | cat
Or make a bash function faketty to encapsulate it:
faketty () {
script -qefc "$(printf "%q " "$@")" /dev/null
}
faketty ls --color=auto | cat
Or in the fish shell:
function faketty
script -qefc "(printf "%q " "$argv")" /dev/null
end
faketty ls --color=auto | cat
(credit goes to this answer)
Use the unbuffer command (as part of the expect suite of commands), unfortunately this requires an extra package install, but it's the easiest solution:
sudo apt-get install expect-dev # or brew install expect
unbuffer -p ls --color=auto | cat
Or if you use the fish shell:
function faketty
unbuffer -p $argv
end
faketty ls --color=auto | cat
This is a great article on how TTYs work and what Pseudo-TTYs (PTYs) are, it's worth taking a look at if you want to understand how the linux shell works with file descriptors to pass around input, output, and signals. http://www.linusakesson.net/programming/tty/index.php