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up vote 1 down vote favorite

I have got this code in file scr.sh:

#!/bin/sh
string='ps -e | less'
$string

And when I execute this script it doesn't work. Why? What I should do to execute command from string variable in shell script?

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1 Answer 1

up vote 4 down vote accepted

It's better to store commands in functions rather than in variables. Functions are great at it. Variables, not at all.

string() {
    ps -e | less
}

string

You could use eval to execute a command that has redirections (>, <) and pipes (|), but I strongly discourage you from doing so.

eval "$string"    # please don't
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Or if it isn't too much to fork then a simple bash -c $string would suffice. Although this method is not as good as a function, it will do the job nonetheless. –  alvits Apr 27 '14 at 19:51
1  
I should also mention, bash -c $string is as bad as eval $string. –  alvits Apr 27 '14 at 20:00
    
Why don't use eval? Only it works in this case. Because really I need to read string from keyboard, doing something with it and then execute. –  dm-kiselev May 7 '14 at 17:13

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