direnv exec has started writing ANSI escape sequences to stderr when stderr isn't a terminal

[frou]

Describe the bug

Hi there - It seems like a recent version of direnv has started making a classic mistake that many programs do, and is unconditionally writing ANSI escape sequences :)

To Reproduce

$ direnv exec . true 2>x.txt

Then open x.txt in a text editor and see that it starts with

\x1B[mdirenv: loading

Expected behavior

When writing to either of stdout/stderr, if they aren't a terminal/TTY then ANSI escape sequences shouldn't be written. So the file x.txt in the example should simply start with:

direnv: loading

Environment

• OS: macOS 12
• Shell: bash
• Direnv version: 2.32.0

[tmatilai]

It seems like a recent version of direnv has started making a classic mistake that many programs do, and is unconditionally writing ANSI escape sequences :)

Agreed that it should check the TTY. The error messages have been printed in red for quite some years, but I guess this came visible to you because of #884 adding the reset code for status log messages.

[zimbatm]

Also, I removed the dependency on tput, which might have done the job for us.