Initially I thought that this would be a perfect job for
dirname, the partner to the better known
basename utility. It's not, though, because
basename /usr/lib/test is "/usr/lib", not just "/usr". So instead, I'd use
cut, a utility I write about in the book too. The
cut utility lets you specify the delimiter for field separation and also lets you specify what field you're interested in, so here's what happens when we put all of that together:
$ echo /usr/lib/test | cut -d/ -f2
usr
You can drop that into a pipeline and if we assume that your list of files is itself in a file called "filelist", you're halfway there with this one line:
cut -d/ -f2 filelist
If you want to prepend the slash, you can do that with
sed, but let's tackle the "unique" part first with
uniq. Since that particular utliity only works if the input is sorted, here's the pipe I have:
cut -d/ -f2 filelist | sort | uniq | sed 's/^/\//'
That'll do everything you want and it's short enough to be an alias!
Hope that helps and good luck with your script writing efforts.
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Good question, I tried this way:
[jsaikia@zorro trap]$ cat dir.names
/usr/local/test
/usr/bin/test
/opt/Tivoli/dat
/opt/lib/test
/tmp/files/test
/tmp/local/test
[jsaikia@zorro trap]$ cat dir.names | awk -F "/" '{print "/"$2}' | sort | uniq
/opt
/tmp
/usr