UNIX for Advanced & Expert Users

Hi,

I have snippet like the following

x="1"
prompt1="hi"

if I say

eval echo \$prompt$x then it is giving o/p "hi"

if I say `eval echo \$prompt$x` here it is giving 1 !

if I add one more escape character i.e.
`eval echo \\$prompt$x` then it is giving "hi"


Can you please explain me why we need to use \\ ( 2 numbers) and what is happening when I execute command with in back quotes ?

I don't undestand what you are going to achive. Using eval in these examples is not making any sense to me. Also when writing variables next to each other, better use curly brackets to not get into problems. Just like "${var1}${var2}" for example.

Hey Thanks for this.
Let me say why I got qery

Code:

prompt1="Empno:" prompt2="Ename"
while [ ${i:=1} -le 2 ]
do
 eval echo \$prompt$i '\\c'
 read val$i
 record="${record}`eval echo \\$prompt$i`|"
done
echo $record

Hope you are now clear why I am asking that question.

Yes. That's what arrays are for usually, eg

Code:

typeset -a prompt
typeset -a val
prompt[0]="Empno:"
prompt[1]="Ename:"
while [ ${i:=0} -le 1 ]
do
 printf "%s" ${prompt[$i]}
 read val[$i]
 record="${record}$( printf "%s|" ${prompt[$i]} )"
done
echo $record

Although you're just concatenating your prompts here. Somehow I'm missing the point where you use the input for something.