p.s. Please post replies to net or send to cgit...@riemann.gsfc.nasa.gov

The csh Bible is "The UNIX C Shell field guide" by Gail & Paul Anderson
- its a very good book. ****

I use "the KORNSHELL Command and Programming Language" for Ksh, I really
didn't much care for this book at first (the index sucks, I find it hard
to locate info. and the explanations and examples are often poor), but
its growing on me, a little. **

Don't try and struggle by w/o a book, a book  will save you considerable
time.

I use tcsh (new, improved csh) as my login shell, but if you are going
to being doing a lot of shell programming, I would recommend taking a look
at ksh.  Ksh generally handles super long command lines (e.g.
grep 'something' <a very long list of files> ) where csh and tcsh
don't - I have found this a major drawback on several occassions.
Ksh also has some other nice features, like pattern matching features,
although the case/switch command is not as good as csh (can't "fall thro'"
to the next "case")  and the "until" iteration command seems to be
particularly lame (if not redundant).

I suspect that some of the new ksh features e.g. [[]] $() and $(<)
make ksh scripts considerably faster that csh scripts, but I have no proof
of it.

My 2p worth.

I had my choice of Bourne shell and csh when I first started, and learned
the script syntax for the former, even though I used csh for a shell.  At
the time, I think that "backwards compatibility" was on my mind.

I've since graduated to ksh, and am glad I never wasted time learning csh
syntax (Ksh syntax is consistent with sh syntax).  I think ksh is a better
shell, too.

Try looking for the special rules that "read" uses for IFS splitting.
(You can read files like /etc/passwd with IFS=:, and empty fields are handled).
And I still haven't found out where is mentions special ~ expansion
rules for PATH assignments. You have to scan the whole book to find
these and others.

Stop looking, they're not in there.  Korn wanted to do away with the
special PATH tilde expansion hack altogether, and the initial versions
of ksh-88 did not include it.  He had to put it back after too many
users complained.

Chet

--
``Someday soon, I'm gonna tell the world about the crying game...''

Chet Ramey                        Internet: c...@po.CWRU.Edu
Case Western Reserve University   NeXT Mail: c...@macbeth.INS.CWRU.Edu

Don't use the csh as a scripting language - it's full of bugs, anomalies
etc. etc. etc. Use it freely as an interactive shell (although there are
better PD things{*filter*} around on the net ie: zsh, bash, tcsh).

ksh is a great language for programming, but it's not a good idea if you
want portability (no doubt ksh will start to spread to more machines). The
bourne shell is on every UNIX machine, has most features you want for
programming are there (unlike the csh ...). Go for it. The manual entry (if one
can understand it) has all the info you'll need.

                                        Martin.
--
Martin Foord.                           MHSnet/ACSnet:  m...@dbsm.oz.au
SBC Dominguez Barry.                    Internet Gateway:
Phone: +61-2-258-2724                   maf%dbsm.oz...@munnari.oz.au

I just started looking at this book, and in the Introduction, one of the
touted features is:

"Tilde Expansion.  The home directory of any user, and the last directory
that you were in, can be referred to symbolically...."

I didn't know about the last directory, but now you tell me it's not
explained in the book??  Sheesh.

At least it's in our man page:
        ~alien  => alien's home directory
        ~       => "my" home directory
        ~+      => $PWD
        ~-      => $OLDPWD   (I didn't know about this one)

Page 146 of The Kornshell Command and Programming Language book says:

        ... Version: In the 06/03/86 and earlier versions of ksh, tilde
        substitution was attempted after each : within the value of an
        assignment statement.

So, for example the following:

        PATH=/bin:/usr/bin:~/bin:

is equivalent to:

        PATH=/bin:/usr/bin:$HOME/bin:

Also, it's not limited to the PATH variable.

At one point during the beta test of ksh, Korn took this feature
out, but since so many people who were using it by then complained,
it was put back [I think this was around the time the book was being
written].  So, as far as I can tell, the book should not list this
as a version specific feature.
--
Larry Cipriani, att!cbvox1!lvc or l...@cbvox1.att.com
"Fight fire with fire, I always say." -- Bugs Bunny

You misunderstand.  The Korn shell will magically expand tildes that
appear after unquoted colons (or maybe it's unquoted tildes after colons)
in assignments to PATH.  This does not obey the normal tilde-expansion-at-
the-start-of-a-word rule, and it's not in the book.

Korn did try to remove this `feature', but had to put it back.

Chet
--
``Someday soon, I'm gonna tell the world about the crying game...''

Chet Ramey                        Internet: c...@po.CWRU.Edu
Case Western Reserve University   NeXT Mail: c...@macbeth.INS.CWRU.Edu

Chet> You misunderstand.  The Korn shell will magically expand tildes
Chet> that appear after unquoted colons (or maybe it's unquoted tildes
Chet> after colons) in assignments to PATH.  This does not obey the
Chet> normal tilde-expansion-at- the-start-of-a-word rule, and it's
Chet> not in the book.

This "for" loop seems to work...

#set dummy ~exptools/adm/bin ~unison/bin $directories; shift #didn't work

for i in ~exptools/adm/bin ~unison/bin
do directories=$directories\ $i; done #get tilde expansion

for i in $directories
do
        #don't add it to PATH if already there
        case $nPATH in *:$i:*|*:$i|$i:*|$i) continue; esac

        #see if the directory really exists
        test -d $i && nPATH=$nPATH${nPATH+:}$i
done
PATH=$nPATH

Although your method is probably better (keeping only one copy of each
directory ... not adding directories that don't exits...) I have to
set several path-like variables so I use something like:

list ()
  {
    IFS=:
    echo "$*"
  }

PATH=$(list ~/bin /bin /usr/bin)
CDPATH=$(list ~ ~/src ~/docs)

This works with both BASH and ksh.

-dave

ps...@andrew.cmu.edu
R746P...@VB.CC.CMU.EDU