Shell Programming and Scripting

Can I use the read command to read the contents of a variable? I'm trying by using the following code and getting nothing back. I'm in a Linux environment.

#!/bin/ksh
IFS=~
VAR1=1~2~3~4
echo $VAR1 | read a b c d
print "$a $b $c $d"

this is working for me!!!

Code:

fnsonlu1-/home/fnsonlu1> cat v
IFS="~"
var="1~2~3~4"
echo "$var"|read -r a b c d
echo $a"\n"$b"\n"$c"\n"$d
fnsonlu1-/home/fnsonlu1> v
1
2
3
4

You need to quote the ~ in the IFS assignment

Code:

IFS="~"

In Bash or Dash you need to group the commands following the pipe.

Code:

#!/bin/sh
IFS="~"
VAR1=1~2~3~4
echo $VAR1 | { read a b c d; echo "$a $b $c $d"; }

mjd_tech : I tried both sets of replies and yours worked...except I could not reference the new variables outside of the brackets. In other words I got the values echoed for a,b,c and d from the echo within the brackets, but when I added the second echo line, I had lost the reference....do I need to do an eval or something to make it global?

IFS="~"
VAR1=1~2~3~4
echo $VAR1 | { read a b c d; echo "$a $b $c $d"; }
echo $a

Code:

#!/bin/ksh
VAR1='1~2~3~4'
set -f
set -- $(IFS='~'; echo $VAR1)
set +f
echo "[$1] [$2] [$3] [$4]"

output is:

Code:

1 2 3 4
1 2 3 4

Oops, I forgot to quote ALL the vars...

Ksh version:

Code:

#!/bin/ksh
IFS="~"
VAR1="1~2~3~4"

echo "$VAR1" | read a b c d
echo "$a $b $c $d"
echo "$a"

# Result
1 2 3 4
1

Bash / Dash version (no pipe, no brackets)

Code:

#!/bin/sh
IFS="~"
VAR1="1~2~3~4"

read a b c d <<EOF
$(echo "$VAR1")
EOF
echo "$a $b $c $d"
echo "$a"

# Result
1 2 3 4
1

This is because Bash creates a subshell for the last process in a pipeline, in this case the read statement.

Thus, the variables a b c d would only be visible to the subshell. I used brackets in the earlier Bash example to group read and echo commands in the same subshell.

In this example, I used a "here document" to feed the read command, instead of a pipe. Thus, the read command does not happen in a subshell, and the a b c d variables are visible to the rest of the script.

Hopefully this makes sense.