UNIX Shell - expansion of wildcards in variables

[Taz]

I'm trying to work around a shell functionality that expands wildcards in variables. Here's an explanation:

1. set a variable that contains asterisks and newline characters with something like:

abc="123***************\n456*********************\n789*******************\n"

2. Use the variable in a for loop and iterate each line held in the variable. So, I set the IFS to be a newline character and use a for loop and echo the variable into it:

IFS='
'

for line in `echo -e "$abc"`
do
# line also contains each file in the current directory as well as each line in the variable abc!
done

The problem is that the echo statement in the for loop exposes the asterisks in the variable abc which then causes the shell to list the contents of the current directory! Now, this is normal shell (ksh) behaviour but I need to be able to loop through my variable line by line and use the exact contents of each line without the shell expanding the asterisks and messing up my for loop.

Any ideas?

[b0redom]

Escape the asterisks.

Or use PERL and split on newline.

[Taz]

My problem is that I cannot escape the asterisks. I run a command that produces multi-line output and then I assign this output to a variable. Unfortunately the output contains lines with multiple asterisks.

[manwithnoname]

Are you sure echo statement does the variable expansion, it might be done inside the do loop. See what out put you get from
echo $line

edit: did see you were using ksh

running under ubuntu 9.10, is this the output you are looking for?

ubuntu@ubuntu:~$ cat test
#!/usr/bin/ksh

abc="123***************\n456*********************\n789*******************\n"

IFS='
'

for line in `echo -e $abc`
do
 echo $line
done


ubuntu@ubuntu:~$ ./test
123***************
456*********************
789*******************
ubuntu@ubuntu:~$

[Taz]

^ Yes, that is the output I am after. What i'm getting is the files in the current directory mixed in with the contents of the variable. I'll try removing the double-quotes when i'm back at work tomorrow. Something is expanding the asterisks!

[Taz]

Now this gets interesting. The script that manwithnoname posted works fine. However, if you have asterisks at the beginning of a line then my terminal session actually hangs!

#!/usr/bin/ksh

abc="***************************************************abc\n\n123***************\n456*********************\n789*******************\n"

IFS='
'

for line in `echo -e $abc`
do
 echo $line
done

The only difference is that I added the following text to the beginning of the variable 'abc':

***************************************************abc\n\n

Can anyone explain why this would cause my shell session to hang? Removing that extra text causes the script to run okay. I think it's something to do with having the asterisks at the beginning of a line and the newline character. It's almost as if the script expands the asterisks to the files in the current directory and the newline character causes the shell to try and execute those files.

[Taz]

As a workaround, I am stripping out asterisks by piping the output to sed as follows:

#!/bin/sh

abc=`echo "***************************************************abc\n\n123***************\n456*********************\n789*******************\n" | sed 's/\*//g'`

IFS='
'

for line in `echo -e $abc`
do
 echo $line
done

I'm not interested in the asterisks. Ultimately I will be running an external command and capturing the out of that command (which contains lines with asterisks).

[manwithnoname]

How are you creating what "abc" is, could you put it in a file (called mydatafile) and read line by line using something like:

while read line
do
echo $line
done < mydatafile

if you cannot use a file, you can could use pipe to connect a script that generates the "abc" data (called generateabcdata) and writes on the stdout, to the script below (called processabcdata) which should read from the stdin. Run the 2 commands: generateabcdata | processabcdata

#!/bin/sh
while read line
do
echo $line
done