Is it possible to set comparison sign as variable?
I want to do something like that:
var1=${1} var2=${2} condition=${3} if [[ "${var1}" "${condition}" "${var2}" ]]; then echo "Warning!" fi ./alert.sh "10" "5" ">" 
2 Answers
Setting it is no problem, it's using it that's difficult. (Your code raises a syntax error.)
You could switch from [[ ]] to test, though it's not exactly the same.
By the way, > is a string operator. You probably wanted -gt, the integer operator. See the link above for a table of operators.
var1="10" var2="5" condition="-gt" if test "${var1}" "${condition}" "${var2}"; then echo "Warning!" fi Output:
Warning! Single square brackets also work (they're equivalent), but for some reason, ShellCheck detects a syntax error, so to make life easier with ShellCheck, I'd say just avoid it, even if that's a bug.
[ "${var1}" "${condition}" "${var2}" ] 
Comments
An other way of doing such work is to construct & launch a second script.
It should be easier to debug (you can see & redo directly the cde)
echo " #!/bin/bash echo "es2 Start" ... write your cdes here ... with parameters you want " > es2
chmod +x es2 ./es2 
4 Comments
chepner
Your quoting is wrong, even ignoring the possibility of the variables themselves containing quotes in their values.
Dri372
It's just an example you can do what you want ... of course not if you want to copy / paste :-) Hope other people will find the tip useful...
chepner
People needing a tip like this will need to be made aware of the pitfalls of this approach, something you did not address.
Dri372
That's precisely why this approach is useful, people can see the real cde (and debug) via the second file ... so I rewrite my answer without "real code"
[[witheval [[.evalwill evaluate whatever string it gets, rather than just the parts you "expect" to be evaluated.