CODEWITHSUNDEEP
linuxbashshellunix
deadcell4
deadcell4

Reputation: 6725

Bash - How to call a function in this scenario

Hello I was wondering what would be the best way break this block of code into functions and 

 case $# in
    1) ports='1-1023'
       host=$1 ;;
    2) ports=$1
       host=$2 ;;
    *) echo 'Usage: portscan [port|range] host'
       exit 1 ;;
esac
# check port range
if [ "$(echo $ports | grep '^[1-9][0-9]*-[1-9][0-9]*$')" != "" ]; then
    firstport=$(echo $ports | cut -d- -f1)
    lastport=$(echo $ports | cut -d- -f2)
elif [ "$(echo $ports | grep '^[1-9][0-9]*$')" != "" ]; then
    firstport=$ports
    lastport=$ports
else
    echo "$ports is an invalid port(s) value"
    exit 2
fi
# check firstport > lastport
if [ $firstport -gt $lastport ]; then
    echo $firstport is larger than $lastport
    exit 3
fi

**and call them in main like this****

# Check parameters and exit 1 if problem
check_parms $#
# Check port range and exit 2 if problem
check_ports $ports
# Check port order and exit 3 if problem
check_order $firstport $lastport

Upvotes: 0

Views: 84

Answers (1)

Dinesh
Dinesh

Reputation: 4559

When you call a bash function, it too has its own $*, $#, $1, .... to reflect that invocation. So you could build a bunch small functions like

function check_parms() {
    local num=$# <----------- I changed this line
    case $num)
    ... etc
}

and then, 

function check_ports() {
    local ports=$1
    if ...
}

etc.

I hope this gives you some ideas for refactoring. In case you were thinking of sourceing the bash script, a good idea might be to unset the functions that you defined at the end of the script.

A nice tutorial at here

In the main block, call it like any other bash function. For example:

echo "hello"
check_parms $*
check_ports $ports
echo "..."

Upvotes: 1

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