UNIX for Dummies Questions & Answers

Post output of those commands:

Code:

# ls -l script.sh
# cat script.sh

Can you please explain what $1 is in the end of the script ??? What is its significance, because thats what I forgot to add to the script which didnt work

Cheers

It is very important. It is shell built-in variable, that holds first argument passed when executing the script, so when you run the script as ./script.sh file, then $1 will contain file's name, later used by Perl one-liner.

Thanks but does this mean if I need to do the same thing with another script I need to add a different variable like $2 ?? or still $1 would work? ... I think it can be $1 but if I'm wrong please correct....
My aim is to learn how can I create a loop to execute the same script over multiple files ..... I tried doing

Code:

./script.sh file*

but gave result for just first file.

Let me know where I am wrong

This is because * is expanded to all the file names before script is executed, so after expansion it looks like: ./script.sh file1 file2 file3 and as you can see there are more arguments passed now. file2 is stored in $2, file3 is in $3 and so on. But there is also variable containing all the arguments passed - $*. You can see below how it can be used to execute that one-liner on all the files:

Code:

#!/bin/sh
for i in $*; do
perl -lane '$a{$F[4]}++;END{for $i (keys %a){print "$i=$a{$i}"}}' $i
done

After modifying script.sh, execute it again with ./script.sh file*

awesome I was imagining a for loop somewhere .... great

Thanks a lot for the clear explanation .... loving learning from you

Cheers !!

---------- Post updated at 04:46 PM ---------- Previous update was at 04:30 PM ----------

This is doing the job but the output doesn't come file by file but as a huge list so I dont know which output is from which file ..... is there a way to change output so that I can distinguish which output is from which file ??

Try:

Code:

#!/bin/sh
for i in $*; do
echo "$i"
perl -lane '$a{$F[4]}++;END{for $i (keys %a){print "$i=$a{$i}"}}' $i
done