topic Re: Why my newcd got problem? in Operating System - HP-UX

Why my newcd got problem?

zhaogui — Mon, 24 Jun 2002 02:24:16 GMT

I found that I have to provide a parameter to "cd" command in order for my newcd to work properly. Can I do without this parameter?

Here is my .kshrc
set -o vi
set -o monitor
alias ll='ls -la'
alias setprmt='PS1=$HOST"["$USER"]:"${PWD##*/}" "'
setprmt
alias cd=newcd
function newcd
{
\cd "$@" >&- || return 1
setprmt
}

Can anybody tell me if the script for newcd is correct or not, why need \cd "$@" >&- and how to interpret it? Does it support null parameter?
Thanks,

Re: Why my newcd got problem?

Ceesjan van Hattum — Mon, 24 Jun 2002 06:21:56 GMT

As far as i can see, your cd is indeed just a bit different than normal:

$@=$1$2$3...
($*=$1,$2,$3... where ,=IFS)
<&- = close standard output

In other words, \cd is just the cd with all arguments concatenated. If it failes (||=OR) it returns 1, else it will continue with setting a nice-looking promt (setprmt=PS1-setting).

if you do a 'cd a /b'
i suppose it will do a
cd a/b
, 'cause it should delete the spaces.

If it was upto me, i would not set this newcd.

Regards,
Ceesjan

Re: Why my newcd got problem?

zhaogui — Mon, 24 Jun 2002 07:04:19 GMT

Here is the error message I got when I simply type 'cd' without any parameter,
myhost[myuser]:opc_op cd
newcd[2]: @: parameter not set
Normal cd will move to my home directory as what 'cd ~' does. How come my newcd cannot?
Other doubts:
1. why there is \ before cd? If I remove it, I will get this,
myhost[myuser]:opc_op cd /usr
ksh: newcd: recursion too deep
2. what is close standard output for &-? Is it the same as normal standard output 1> ?

Re: Why my newcd got problem?

zhaogui — Mon, 24 Jun 2002 07:11:56 GMT

Another interesting doubt is, why the .kshrc always run after all commands in .profile finished?

.kshrc is the same as mentioned above.
Here is .profile,
# Set up the shell variables:
EDITOR=vi
export EDITOR

ENV='${START[(_$-=1)+(_=0)-(_$-!=_${-%%*i*})]}'
START=$HOME/.kshrc
export ENV START
LANG=C ; export LANG
PWD=$HOME ; export PWD
SHELL=/bin/ksh ; export SHELL
HOST=`uname -n` ; export HOST
USER=`logname` ; export USER
echo $$

Re: Why my newcd got problem?

Peter Kloetgen — Mon, 24 Jun 2002 07:18:05 GMT

Hi Zhaogui,

your .kshrc is run after the .profile because you have the entry:

ENV=.........

This variable tells your system, to source the .kshrc- file for each new kornshell which is started.

and your newcd should work better, if you first run a test- command, to check if there are any parameters given to the function:

if test $# -ne 0
then
your_function_command
else
cd
fi

Allways stay on the bright side of life!

Peter

Re: Why my newcd got problem?

Peter Kloetgen — Mon, 24 Jun 2002 07:24:18 GMT

Hi again,

of course the whole construction has to look like this:

function newcd
{
if test $# -ne 0
then
\cd "$@" >&- || return 1
setprmt
else
cd
fi
}

Allways stay on the bright side of life!

Peter

Re: Why my newcd got problem?

zhaogui — Mon, 24 Jun 2002 07:37:14 GMT

Good progress! it can accept cd without any parameter, but still got another error message. here it is,
myhost[myuser]:opc_op cd /usr
myhost[myuser]:usr cd
ksh: newcd: recursion too deep

I suspect this could be due to the endless loop of recursion, because cd calls newcd first and then call cd again, and call newcd again and again...

Re: Why my newcd got problem?

Peter Kloetgen — Mon, 24 Jun 2002 07:46:25 GMT

Hi Zhaogui,

what happens if you delete the ">&-"?

And try to do the same script without "|| return 1".

Allways stay on the bright side of life!

Peter

Re: Why my newcd got problem?

zhaogui — Mon, 24 Jun 2002 23:29:04 GMT

I got it, here is my new .kshrc,
set -o vi
set -o monitor
alias ll='ls -la'
alias setprmt='PS1=$HOST"["$USER"]:"${PWD##*/}" "'
setprmt
alias cd=newcd
function newcd
{
if test $# -ne 0
then
\cd "$@" >&- || return 1
setprmt
else
\cd
setprmt
fi
}
echo "End of kshrc:"
You see, now I understand why I must put \ before every cd and why we need to create such a newcd in ksh environment.
Thank you very much for your help. I will assign points to you.