Comment by TobTobXX

4 days ago

Many unix tools already print less logging when used im a script, ie. non-interactively. (I don't know how they detect that.) For example, `ls` has formatting/coloring and `ls | cat` does not. This solution seems like it would fit the problem from the article?

4 comments

TobTobXX

zahlman 4 days ago

> I don't know how they detect that.

The OS knows (it has to because it set up the pipeline), and the process can find out through a system call, exposed in C as `isatty`: https://www.man7.org/linux/man-pages/man3/isatty.3.html

> This solution seems like it would fit the problem from the article?

Might not be a great idea. The world is probably already full of build tools pipelines that expect to process the normal terminal output (maybe with colours stripped). Environment variables like `CI` are a thing for a reason.

skydhash 4 days ago

There’s a function isatty that detect if a file descriptor (stdout is one) is associated with a terminal

https://man.openbsd.org/man3/ttyname.3

I believe most standard libraries has a version.

sdsd 4 days ago
I was about to comment the same thing. Usually I don't call the function directly, but via the tty command in my shell scripts:
if tty -s; then echo "Standard input is a TTY (interactive mode)." else echo "Standard input is not a TTY (e.g., piped or redirected)." fi
Now I wonder how _isatty_ itself detects whether a file descriptor is associated with a terminal!
- skydhash 4 days ago
  
  In OpenBSD, with the fcntl system call
  https://github.com/openbsd/src/blob/master/lib/libc/gen/isat...
  https://man.openbsd.org/fcntl
  https://github.com/openbsd/src/blob/master/sys/sys/fcntl.h
  https://github.com/openbsd/src/blob/ba496e5267528b649ec87212...
  https://github.com/openbsd/src/blob/ba496e5267528b649ec87212...