[TriLUG] missing packages help
jsnthegod at hotmail.com
Sun Sep 17 17:03:54 EDT 2006
thanks for the info, it cleared some things up, and made others foggy, its
just something i will have to clarify on my own to myself later on :)
again, thanks for the help and info
>From: Alan Porter <porter at trilug.org>
>Reply-To: Triangle Linux Users Group discussion list <trilug at trilug.org>
>To: Triangle Linux Users Group discussion list <trilug at trilug.org>
>Subject: Re: [TriLUG] missing packages help
>Date: Sun, 17 Sep 2006 14:59:37 -0400
>>i was trying to to show all the files that begain with lib. i was looking
>>to see if i could find something similar to the libobdcinst
>You were trying to show all of the PACKAGES that started with "lib". You
>were not trying to show all of the FILES IN THE CURRENT DIRECTORY that
>started with "lib".
>It's a subtle, but very important distinction. Once you figure out what
>the shell is doing with what you type, things tend to make a lot more
>>>When there are no files that begin with "lib", the shell can do one of
>>>(1) replace "lib*" with ""
>>>(2) keep the "lib*"
>>im confused about option 1)... but thats what they made man pages for, ill
>>have to look into that later.
>The shell replaces wildcards before it calls the command. Here's some
>(expand wildcards, no wildcards, so just do "ls")
>$ ls *.mp3
>(expand wildcards, so "ls song1.mp3 song2.mp3")
>$ shopt -s nullglob ; ls *.doc
>(expand wildcards, no matches, nullglob is set, so "ls ")
>$ shopt -u nullglob ; ls *.doc
>(expand wildcards, no matches, nullglob is not set, so "ls *.doc")
>no such file "*.doc"
>This is what I meant by "Each of these may seem intuitive under different
>circumstances". In this case, it seems more intuitive to leave nullglob
>unset and get an error message from "ls". "ls" had no idea what to do when
>it was passed "*.doc". It was looking for a file called, literally,
>If you'd like to see a case there it's more intuitive to have nullglob set,
>try "touch *.ogg" in an empty directory. What did it do? If nullglob was
>set, it would create a file called "*.ogg". Not what you thought, was it?
>The "touch" command simply did the best it could with what the shell told
>it to do. The shell tried to expand the wildcard, failed, and passed the
>wildcard on to "touch". The only thing "touch" knew how to do was create
>an empty file called "star-dot-ogg".
>For people who come from the DOS world, it might seem weird for the shell
>to do the filename wildcard expansion. DOS programmers typically had to do
>that themselves. So each DOS program tended to handle wildcard expansion a
>little differently. Ugh.
>An exercise for the reader... which is more conservative when using "rm
>*.pdf", setting nullglob or not? This is why I leave nullglob OFF (I set
>it with a "shopt -u nullglob" in my .bashrc).
>Anyway, it sounds like you're on your way with the libraries. I hope this
>little lesson in bash and other unix shells has not been too much of a
>diversion. And I hope it sheds some light on what might otherwise seem
>like unpredictable behavior.
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