Question

I need pass a series of couples values which are arguments for a c++ software. So I wrote this script:

while read randomNumbers; do
                lambda = $randomNumbers | cut -f1 -d ' '
                mi = $randomNumbers | cut -f2 -d ' '
                ./queueSim mm1-queue $lambda $mi 
done < "randomNumbers"          

where the first arg is the first value for each line in the file “randomNumbers” and the second one in the second value (of course). I got a segfault and a “command not found”.

How can I assign to lambda and mi valus got from the line and pass this variable to c++ software?

Answer 1

There’s no need for cut. Let read split the line for you:

while read lambda mi; do
    ./queueSim mm1-queue $lambda $mi 
done < randomNumbers

Note that it is also commonly used in conjunction with IFS to split the input line on different fields. For example, to parse /etc/passwd ( a file with colon separated lines ), you will often see:

while IFS=: read username passwd uid gid info home shell; do ...