How to do operations with form values? - ruby-on-rails

Question

so i have a form with 3 text fields, in two of them, users enters a code (and OID), which i use to run a command (snmpbulkwalk). So i want to store the outputs of those commands in a variable, lets say var1 and var2.
[]
But then, in the last text field, i want to do and operation with these variables, like: var1 - var2.
So far i tried this:
#var1 = "nice -n 19 snmpbulkwalk -v 2c -c %snmp_community
%sensor_ip "+ "#{monitor_category_params[:oid].strip}"+" | awk
'/kB$/{ $(NF-1)= $(NF-1)*1024;} {print $0}' | sed 's/ [A-Za-
z]*$//' | awk '{print $NF}' | grep -o '[[:digit:]]*' | paste -s
-d';' -"
puts("var1 = " + "#{#var1}");
#var2 = "nice -n 19 snmpbulkwalk -v 2c -c %snmp_community
%sensor_ip "+ "#{monitor_category_params[:oid2]}"+" | awk
'/kB$/{ $(NF-1)= $(NF-1)*1024;} {print $0}' | sed 's/ [A-Za-
z]*$//' | awk '{print $NF}' | grep -o '[[:digit:]]*' | paste -s
-d';' -"
puts("var2 = " + "#{#var2}");
#var3 = "#{monitor_category_params[:snmp_oper].strip}"
puts("var3 with {} = " + "#{#var3}");
system = '$(#{#var3})'
puts(system(system));
The thing is i dont know how to store the output of the shell command "nice -n 19 ...blabla" in the variable. I used exec and backticks like this:
exec "nice -n 19 snmpbulkwalk -v 2c -c %snmp_community %sensor_ip "+ "#{monitor_category_params[:oid].strip}"+" | awk '/kB$/{ $(NF-1)= $(NF-1)*1024;} {print $0}' | sed 's/ [A-Za-z]*$//' | awk '{print $NF}' | grep -o '[[:digit:]]*' | paste -s -d';' -"
but it gives me this error, which i dont get it since the command is well formatted.
sh: -c: línea 0: EOF inesperado mientras se buscaba un `)' coincidente
sh: -c: línea 1: error sintáctico: no se esperaba el final del fichero
I dont know if im losing arguments (%snmp_community or %sensor_ip), but the final result should be something like system = number - number. but i only get system = var1 - var2, which is not doing nothing since i want the outputs of the commands, not the name of the variables.
sorry if didnt explain myself good, thank you in advance.

Answer 1

So assuming this is related with ruby or ruby on rails
#var1 and #var2 are instance variable of a method in some class.
You can directly use the backticks directly to save to output from the shell command
#var1 = `ls`
p #var1
However, some bash commands do not return a string value directly.
I have not used snmpbulkwalk till now but $PATH might be similar in a way
#var1 = `echo $PATH` #add you own shell code here to check
p #var1