Are my Linux symbolic links acting correctly?

Posted by Andy Castles on Super User See other posts from Super User or by Andy Castles
Published on 2010-06-11T12:57:49Z Indexed on 2010/06/11 14:03 UTC
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Hi all

I've been using Linux on and off for the last 15 years and today I came across something in bash that surprised me.

Setup the following directory structure:

$ cd /tmp
$ mkdir /tmp/symlinktest
$ mkdir /tmp/symlinktest/dir
$ mkdir /tmp/symlinktarget

Now create two sym links in symlinktest pointing to symlinktarget:

$ cd /tmp/symlinktest
$ ln -s ../symlinktarget Asym
$ ln -s ../symlinktarget Bsym

Now, in bash, the following tab completion does strange things. Type the following:

$ cd dir
$ cd ../A[TAB]

Pressing the tab key above completes the line to:

$ cd ../Asym/

as I expected. Now press enter to change into Asym and type:

$ cd ../B[TAB]

This time pressing the tab key completes the link to:

$ cd ../Bsym[space]

Note that there is now a space after the Bsym and there is no trailing slash.

My question is, why when changing from the physical directory "dir" to Asym it recognises that Asym is a link to a directory, but when changing from one sym link to another, it doesn't recognise that it's a link to a directory?

In addition, if I try to create a new file within Asym, I get an error message:

$ cd /tmp/symlinktest/Asym
$ cat hello > ../Bsym/file.txt
-bash: ../Bsym/file.txt: No such file or directory

I always thought that symlinks were mostly transparent except to programs that need to manipulate them. Is this normal behaviour?

Many thanks,

Andy

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