Question

I use getopts to obtain a MAC address and grep that MAC address through log files. It looks like this:

#!/bin/bash

while getopts ":m:hx:" opt; do
  case $opt in
    m)
        cat /var/log/vmlog/Verimatrix.log | grep $OPTARG | grep VCAS080455
        cat /var/log/vmlog/Verimatrix.log | grep $OPTARG | grep VCAS080285
        cat /var/log/vmlog/Verimatrix.log | grep $OPTARG | grep VCAS080290
      ;;
    h)
        echo "./search_mac.sh -m <mac address> will filter the logs by mac address"
        echo "./search_mac.sh -h will print this message"
      ;;
    \?)
      echo "Invalid option: -$OPTARG" >&2
      ;;
  esac
done

I want to export the result to a file when the -x option is used:

./search_mac.sh -m 00067B6D87F0 -x /home/nico/extract.txt

I don’t understand at this point how to obtain the argument from -x to be into my m) part of my case.

A little help would be great.

Thanks

Answer 1

I think the best approach is to save the values of the option-arguments in shell variables, and then run your commands at the end:

#!/bin/bash

m_arg=
x_arg=

while getopts ":m:hx:" opt; do
  case $opt in
    m) m_arg="$OPTARG" ;;
    x) x_arg="$OPTARG" ;;
    h)
        echo "./search_mac.sh -m <mac address> will filter the logs by mac address"
        echo "./search_mac.sh -h will print this message"
        exit 0
      ;;
    \?)
      echo "Invalid option: -$OPTARG" >&2
      exit 1
      ;;
  esac
done

if [[ "$x_arg" ]] ; then
    exec > "$x_arg"          # redirect STDOUT to argument of -x
fi

< /var/log/vmlog/Verimatrix.log grep -- "$m_arg" | grep VCAS080455
< /var/log/vmlog/Verimatrix.log grep -- "$m_arg" | grep VCAS080285
< /var/log/vmlog/Verimatrix.log grep -- "$m_arg" | grep VCAS080290

That said . . . this option doesn’t seem all that useful to me, since -x /home/nico/extract.txt would just mean the same thing as > /home/nico/extract.txt. Am I missing something?