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ksh vs perl strange interaction.

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# 1  
Old 01-09-2011
ksh vs perl strange interaction.
Hello everybody,

I isolated an issue: please try the following script (under AIX)

Code:
#!/usr/bin/ksh93


echo "Before Perl: \c"
read line
echo "|$line|"

perl -e 'print "Perl invocation";'
echo

echo "After Perl: \c"
read line
echo "|$line|"

On the first input, type Ctrl-D. It works
On the second input, type Ctrl-D. You'll need to type it twice.

Now, change the script to use ksh instead of ksh93. It works fine.

Smilie

What's wrong? Any workaround?

Jacques.
Last edited by jlovi; 01-09-2011 at 10:58 PM..
# 2  
Old 01-09-2011
Does'nt appear to be related to perl it does it to me without any command in-between:

Code:
#!/usr/bin/ksh93
 
echo "1st: "
read line
echo "|$line|"
 
echo "2nd: "
read line
echo "|$line|"

##Update##, seems to be ok if you use /bin/read instead of the ksh93 internal read function.
# 3  
Old 01-09-2011
You're right (quite late here to have a completely clear mind Smilie).

This has the problem too:

Code:
#!/usr/bin/ksh93


echo "a"| read a

echo "After Perl: \c"
read line
echo "|$line|"

---------- Post updated at 04:43 AM ---------- Previous update was at 04:13 AM ----------

Quote:
Originally Posted by Chubler_XL
##Update##, seems to be ok if you use /bin/read instead of the ksh93 internal read function.
Thanks for this idea... it could have worked. Unfortunately, in AIX, here the /usr/sbin/read content:

Code:
#
# This shell script gets installed in /usr/bin to provide an exec()-able
# version of certain shell builtins:
#       alias           command         getopts         umask
#       bg              fc              jobs            unalias
#       cd              fg              read            wait
#       hash            type
#
# These are also builtins, but already have historical version in /usr/bin:
#       false           kill            newgrp          true
#
command=`/usr/bin/basename $0`          # Invoke the ksh builtin
if [ "$command" = "type" ]
then
        whence -v "$@"
elif [ "$command" = "hash" ]
then
        alias -t - "$@"
else
        $command "$@"
fi

Smilie
# 4  
Old 01-09-2011
Sounds like you need a workaround, this will work for reading 1 variable if that's all you need.

Code:
#!/usr/bin/ksh93

line=$(head -1)
echo "|$line|"
line=$(head -1)
echo "|$line|"

# 5  
Old 01-09-2011
Thanks for your great ideas!

Unfortunately (I think this is the last trick), I need to emulate "read -r line" Smilie



### UPDATE ###

This seems to work. I'll try it in my program.

Code:
#!/usr/bin/ksh93


echo "a"| read a

echo "1: \c"
line=$(head -1|(read -r line;echo "$line"))
echo "|$line|"
echo "2: \c"
line=$(head -1|(read -r line;echo "$line"))
echo "|$line|"

Last edited by jlovi; 01-10-2011 at 04:25 AM..
# 6  
Old 01-10-2011
How about this:

Code:
line=$(echo $(head -1) )

# 7  
Old 01-10-2011
Well, well, I was wrong telling that this was the last trick I needed.

In fact, I need to capture Ctrl-D and Ctrl-C, differenciating them. If I type something like "\n$1", I should exactly get these characters.

Got something like this:

Code:
#!/usr/bin/ksh93
line=$(trap 'line=""' INT;head -1|(set -f;read -r line;print -r "$?:$line") 2> /dev/null)
[ "X$line" != "X" ] && read_res=$(print -r "$line"|cut -f1 -d:)
line=$(print -r "$line"|cut -f2- -d:)

Tested successfully on Linux (Fedora) and AIX

Works in ksh. Core dump in ksh93! Smilie

SmilieSmilieSmilie
Last edited by jlovi; 01-10-2011 at 02:33 AM..
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