john.parnefjord.se Reflections & findings

Had this annoying message popping up when running a script on Ubuntu 8.0.4 LTS. The message read:

shift: N: can't shift that many

On Debian it works fine. The reason for this is the use of different shells in Debian and Ubuntu. Debian is using bash and Ubuntu is using dash. Check the symlink /bin/sh on the different distributions.

To reproduce save the following to a file named test_shift.sh:

#!/bin/sh

while shift; do
echo $1
done

Running the script emits on Ubuntu emits the following message on Ubuntu 8.0.4 LTS:

user@server:~$ ./test_shift.sh test1 test2 test3 test4 test5
test2
test3
test4
test5


shift: 7: can't shift that many

On Debian Lenny it runs without a fuzz. So, what to do? Well, one could either do an ugly hack like this:

#!/bin/sh

shift 1;
while [ "$#" != "0" ]; do
echo $1;
shift;
done

or just change the shebang to point to bash, ie #!/bin/bash. I will choose the latter way.

// John