Question

I am new to Shell script. Just have a small question about some script I wrote.

pkgs="./cppcheck-1.48.tar.bz2 ./sshpass-1.04.tar.gz"
for pkg in $pkgs ; do
echo ${pkg} | grep -qE "bz2$"

if [ $? ] ; then
                echo "here1"
else
                echo "here2"            
fi

done

It always prints here1, i.e. if condition is always true. I am not able to pin point any reason for it till now. Please point me towards right direction.

I know I can use shell’s switch command. Just want to know what is wrong with this. Shell is /bin/bash

[EDIT] – switch statement works flawlessly. For those who face this problem some other time

case ${pkg} in
     *bz2) echo "here1";;
     *) echo "here2";;
esac

Answer 1

if [ $? ] does not work as you might expect:

$ false ; if [ $? ] ; then echo "true" ; else echo "false" ; fi 
true
$ true ; if [ $? ] ; then echo "true" ; else echo "false" ; fi 
true

It’s easy enough to fix by comparing against 0 explicitly:

$ false ; if [ $? -eq 0 ] ; then echo "true" ; else echo "false" ; fi 
false
$ true ; if [ $? -eq 0 ] ; then echo "true" ; else echo "false" ; fi 
true

So for your script:

pkgs="./cppcheck-1.48.tar.bz2 ./sshpass-1.04.tar.gz"
for pkg in $pkgs ; do
echo ${pkg} | grep -qE "bz2$"

if [ $? -eq 0 ] ; then
                echo "here1"
else
                echo "here2"            
fi

done

here1
here2