nixCraft 🐧Sep 22, 2024
Quiz: How do you print the value of the $PWD shell variable in #Linux or #Unix? Choose one answer only.
awk 'BEGIN {print ENVIRON["PWD"]}'
3%
cat <<<"$PWD"
1.4%
echo "$PWD"
92.8%
printf "%s\n" "$PWD"
2.8%
Poll ended at .
Show threadSpaceLifeForm

@nixCraft

cat /proc/cwd

You can not trust ENVIRONMENT

There are issues with getenv(), putenv(), and setenv(). The semantics are not consistent and can be abused.

Sep 22, 2024 at 11:51pmWeb
Show threadFlounderSep 23, 2024
@SpaceLifeForm @nixCraft hang on for real? And here I thought I was being silly when the obvious answer is `pwd`
Show threadSpaceLifeFormSep 23, 2024

@fl0und3r @nixCraft

The pwd executable inherients the ENVIRONMEMT via fork() and execve() from the parent process.

If the enviroment variables have been corrupted already, then there could be turtles.

Most code does not call chdir() so using PWD probably did not change.

But, if the software in question creates addiitonal environment variables that point to subdirectories, there could be issues, especially if there are libraries involved that have not been vetted via source code review.

Show threadFlounderSep 23, 2024
@SpaceLifeForm @nixCraft I'm having a hard time convincing `getcwd` that I'm somewhere I'm not by messing with the environ. presumably this is some deep magic beyond my (limited) understanding? I guess my takeaway is to trust `getcwd` and not `getenv`?
Show threadSpaceLifeFormSep 23, 2024

@fl0und3r @nixCraft

What platform? What libc?

Show threadFlounderSep 23, 2024
@SpaceLifeForm @nixCraft `Ubuntu GLIBC 2.35-0ubuntu3.8`
linux mint running Kernel 6.8.0-45-generic x86_64