contents of origlist
$var1
$var4
$var3
$var2
contents of testparsher.sh
#!/bin/bash
var1="Smith^John"
var2="998877"
var3="member"
var4="12"
cat /dev/null > file.txt
filename=origlist
while read line; do
echo $line >> file.txt
done < "$filename"
the file.txt I want is:
Smith^John
12
member
998877
the file.txt I'm getting is
$var1
$var4
$var3
$var2
So what's the syntax to get the loop to see the parsed text as the preloaded variables?
Thank you so much for your time.
You can do this without 'eval' by using "indirect expansion" (see the Bash manual page for an explanation):
while read var || [[ $var ]] ; do
varname=${var#$}
printf '%s\n' "${!varname}"
done <"$filename" >file.txt
The '[[ $var ]]' is necessary to allow for an unterminated last line in the input file.
The '$' has to be removed from the variable name. Does it need to be in the input file?
Use 'printf' instead of 'echo' in case the variable value begins with an 'echo option.
eval introduces a huge security risk if the contents of the input file are modified. Using indirect parameter expansion, the worst that can happen is that unexpected input will cause a bad substitution error.you need to use eval :
#!/bin/bash
var1="Smith^John"
var2="998877"
var3="member"
var4="12"
cat /dev/null > file.txt
filename=origlist
while read line; do
eval echo $line >> file.txt
done < "$filename"
eval here is strongly discouraged. Arbitrary code could be inserted into origlist, and this code will happily execute it.You are looking for eval, but it comes with a lot of caveats.
Or perhaps you are looking for a here document.
cat <<____HERE >file.txt
$var1
$var4
$var3
$var2
____HERE
file.txt exists prior to the variables it references being set.