How does a program like less handle both piped stdin and keyboard input?

Question

If I run, for example, ifconfig | less, the less program manages to at the same time:

Capture output of ifconfig through the standard input where the output of ifconfig is piped
React to user's keyboard input and be interactive

I never gave this much thought, but as I tried to write a program with functionality similar to less, I got confused: how does it manage to do both at the same time, and what does it do to implement 2, as it's clearly not the standard input?

See this [question](https://stackoverflow.com/questions/43947363/detect-if-a-command-is-piped-or-not) for a solution in Go. It will be similar in other languages. — Matt, Jun 21 '22 at 00:12

score 1 · Accepted Answer · answered Jun 21 '22 at 02:51

1

It reads keyboard input from /dev/tty instead of from stdin.

answered Jun 21 '22 at 02:51

Joseph Sible-Reinstate Monica

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How does a program like less handle both piped stdin and keyboard input?

1 Answers1