Cfrtjryk

Is it a bad idea to include else's when not needed to make the logic more clear ? I've done this more with PHP with longer drawn out if/else's but if you look at the following code (bash) you can get the gist of what I'm saying. Again it's not the most useful example since we are really comparing the same thing 'user' :

How most people do it:

for user in $(awk -F: '($3 < 1000) {print $1 }' /etc/passwd); do

    if [[ "${user,,}" == "root" ]] ; then

        echo "usermod -L $user" 

    elif [ $user != "sync" ] && [ $user != "shutdown" ] && [ $user != "halt" ] ;then

        echo "usermod -s /usr/sbin/nologin $user"

    fi

done

Alternative version :

for user in $(awk -F: '($3 < 1000) {print $1 }' /etc/passwd); do

    if [[ "${user,,}" == "root" ]] ; then

        echo "usermod -L $user" 

    else

        if [ $user != "sync" ] && [ $user != "shutdown" ] && [ $user != "halt" ] ;then

              echo "usermod -s /usr/sbin/nologin $user"

        fi

    fi

done

Thoughts? I personally like the 'alternative', usually keeps me out of trouble more often and I find it easier to read.

UPDATE: going to provide a more "complex" example to show the needlessness of strict use of elif :

Using elif religiously :

for user in $(awk -F: '($3 < 1000) {print $1 }' /etc/passwd); do

    if [ "$user" == "root" ] && ! isAdmin ; then

        echo "command1" 

    elif [ $user != "sync" ] && [ $user != "shutdown" ] && [ $user != "halt" ] && ! isAdmin ;then

         echo "command2" 

   elif [ $user != "sync" ] && [ $user != "shutdown" ] && [ $user != "halt" ] &&  isAdmin ;then

        echo "command3" 

    fi

done

Breaking it down a bit :

   for user in $(awk -F: '($3 < 1000) {print $1 }' /etc/passwd); do

        if isAdmin ;then

            if [ $user != "sync" ] && [ $user != "shutdown" ] && [ $user != "halt" ] ;then

                echo "command3" 

            fi

        else 

            if [ "$user" == "root" ] ; then

                echo "command1" 

            elif [ $user != "sync" ] && [ $user != "shutdown" ] && [ $user != "halt" ] ;then

                echo "command2" 

            fi  

        fi

    done

So what right ? Well my point is that one is more clear to it's intentions IMO and hence easier to debug.

First of all, the pattern if (a==b) ... elif (a==c) is why switch statements exist. In bash, read about them here:

http://tldp.org/LDP/Bash-Beginners-Guide/html/sect_07_03.html

More generally - yes, using an else where an elif will suffice is a bad idea. It unnecessarily lengthens the code without any benefit to legibility. If you're concerned about the legibility of a very long segment of code, you have another problem: you need to subdivide the code into functions so that the blocks within the if statements are more legible.