csh/sh for loop - how to?

Question

i'm trying to write a for loop that executes 2 scripts on FreeBSD. I don't care if it's written in sh or csh. I want something like:

for($i=11; $i<=24; $i++)
{
   exec(tar xzf 'myfile-1.0.' . $i);
   // detect an error was returned by the script
   if ('./patch.sh')
   {
      echo "Patching to $i failed\n";
   }
}

Does anyone know how to do this please?

Thanks

Answer 1

The typical way to do this in sh is:

for i in $(seq 11 24); do 
   tar xzf "myfile-1.0$i" || exit 1
done

Note that seq is not standard. Depending on the availability of tools, you might try:

jot 14 11 24

or

perl -E 'say for(11..24)'

or

yes '' | nl -ba | sed -n -e 11,24p -e 24q

I've made a few changes: I abort if the tar fails and do not emit an error message, since tar should emit the error message instead of the script.

Answer 2

Wow! No BASH. And probably no Kornshell:

i=11
while [ $i -le 24 ]
do
    tar xzf myfile-1.0.$i
    i=`expr $i + 1`
    if ./patch.sh
    then
        echo "patching to $i failed"
    fi
done

Written in pure Bourne shell just like God intended.

Note you have to use the expr command to add 1 to $i. Bourne shell doesn't do math. The backticks mean to execute the command and put the STDOUT from the command into $i.

Kornshell and BASH make this much easier since they can do math and do more complex for loops.

Answer 3

csh does loops fine, the problem is that you are using exec, which replaces the current program (which is the shell) with a different one, in the same process. Since others have supplied sh versions, here is a csh one:

    #!/bin/csh
    set i = 11
    while ($i &lt 25)
        tar xzf "myfile-1.0.$i"

        # detect an error was returned by the script   
        if ({./patch.sh}) then     
            echo "Patching to $i failed"   
        endif
        @ i = $i + 1
    end

Not sure about the ./patch.sh are you testing for its existence or running it? I am running it here, and testing the result - true means it returned zero. Alternatively:

        # detect an error was returned by the script   
        if (!{tar xzf "myfile-1.0.$i"}) then     
            echo "Patching to $i failed"   
        endif