Shells and built-ins

Shells and built-ins

Post by James J. Yort » Fri, 31 Jan 1992 23:35:50



|> I have a problem which I dont understand and am looking for
|> help.  I have a user who is running csh and the path is set
|> to use the version of echo whose syntax is 'echo -n abc'
|> rather than 'echo abc\c'.  Now this user invokes a shell script
|> whose first line is '#!/bin/ksh'.  In this script is the
|> command "echo 'abc\c'".  And the problem is that the echo produces
|> the string abc\c.  In the ksh echo is a built-in using the \c notation.
|> So how come it aint doing it?
|>
|> Any ideas?  Appears invoking the shell is not having it grab
|> the built-ins.
|>
|>  Will Renkel - Motorola - Cellular

I maintain ksh (88f) at the same facility where Will works and have
talked to him off-line about this.

No problem exists.  Ksh is using the builtin.  On our system, Sun OS 4.0.3,
it appears the echo builtin can behave differently depending on where
your $PATH has /bin specified.

The ksh documentation mentions something about this too:

Quote:>ECHO_N  Set when /bin/echo -n does not echo at all.  This causes the
>            echo builtin to handle echo like BSD echo when at run time
>            the shell would find echo in the /bin directory.

Again, no problem exists.

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James J. Yorton                       | Telephone:  +1 708-632-6695
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Shells and built-ins

Post by Donn Ca » Sat, 01 Feb 1992 09:40:06



Quote:>No problem exists.  Ksh is using the builtin.  On our system, Sun OS 4.0.3,
>it appears the echo builtin can behave differently depending on where
>your $PATH has /bin specified.

Well, the echo builtin certainly behaves differently on one of our systems,
depending on $PATH.  This only happens on our RISC Ultrix (4.2) system, and
it only affects "echo", not "print".  I was mystified, but now I suppose that
it must have something to do with the above-mentioned hack.

; ksh
$ Version 11/16/88                
$ PATH=
$ echo $PATH
Memory fault

        Donn Cave, University Computing Services, University of Washington


 
 
 

1. shell built ins

hi everyone,

i still try to get which done so that it knows about the shell built-ins
like exit etc...
i worked on it but still it won't run. i am pretty sure it is just a small
mistake. please help me out here.

thanks a lot
joyce

opath=$PATH
PATH=
($1 2> /dev/null ) && (echo 'built in shell' :exit 0)
echo x
PATH=/bin:/usr bin
case $# in
0)      echo 'Usage: which command' 1>&2; exit 2
esac
                for i in `echo $opath | sed  's/^:/.:/
                                                             s/::/:.:/g
                                                             s/:$/:./
                                                             s/:/ /g'`
do
                      if test -x $i/$1             # this is /bin/test
                          then                         # or /usr/bin/test
only
               echo $i/$1
               exit 0              # found it
      fi
done
exit 1                              #not found

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