How to execute string command in a variable?

Question

Say I have a variable:

T=6

And another variable called 'line' that I read from a file and that contains the following string/text:

echo "$T"

Now I want to execute the command written in 'line' so I'll get:

Just like what I will get if will just type the command:

echo "$T"

And get:

I tried to use:

$line

But I got:

"$T"

Thanks in advance for the help.

Your variable line should be line=echo "$T". Then you can use echo $line. — iqstatic
– iqstatic, Commented Nov 21, 2014 at 11:24

nu11p01n73R · Accepted Answer · 2014-11-21 10:35:58Z

2

eval is what you are looking for

For example consider

$ T=6
$ line='echo "$T"'
$ eval $line
6

From man pages

eval [arg ...]
              The  args  are  read  and concatenated together into a single command.  This command is then read and executed by the shell, and its exit
              status is returned as the value of eval.  If there are no args, or only null arguments, eval returns 0.

answered Nov 21, 2014 at 10:35

nu11p01n73R

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PM 2Ring Over a year ago

Ob-link to Eval command and security issues "eval" is a common misspelling of "evil".

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