4

Let's say we have ./a and ./b directories. Then we create a symlink using ln -s a x and entering it cd x The pwd would be x

Then in another terminal we change the x so that it pointed to b. But the first one would still return x for pwd which is not consistent anymore.

So is there a way for current terminal (bash) to alert/warn if the current path is the obsolete symlink?

2

Here's an approach which uses the fact that bash does command expansion on $PS1 to test to see if . and $PWD have the same inode in the prompt:

PS1='$([[ $(stat -Lc%i $PWD 2>/dev/null) == $(stat -c%i .) ]] || echo "\[\e[1;31m\]PWD invalid or changed \[\e[m\]")'"$PS1"
2

I don't believe there is any way to accomplish this with just regular Bash. You could setup inotify so that it would watch a given directory and then notify the user, typically through email, but there are likely ways to pipe these messages back into a user's shell/environment.

But these notifications would be broad in the sense that they would just come to the users when the links were changed/broken, they wouldn't be contextual, i.e. they wouldn't be sent only when the user was actual in these said directories.

Example

Terminal #1:

$ mkdir $HOME/tst
$ inotifywait -mr $HOME/tst
Setting up watches.  Beware: since -r was given, this may take a while!
Watches established.

Terminal #2:

$ mkdir somedir

Terminal #1:

/home/saml/tst/ CREATE,ISDIR somedir
/home/saml/tst/ OPEN,ISDIR somedir
/home/saml/tst/ CLOSE_NOWRITE,CLOSE,ISDIR somedir

Terminal #2:

$ rmdir somedir

Terminal #1:

/home/saml/tst/ DELETE,ISDIR somedir
/home/saml/tst/somedir/ DELETE_SELF

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