help with counting variables

me. · 11-21-2011, 05:16 PM

HI have here script that should copy file by file to different directory
but I think I messed with the counter, help figuring out appreciated.

Code:

#!/bin/bash
dir=/home/andre/Documents/Scripts/Copy
files=$(pwd | ls -m )
counter= #counter set to number of files counted with wc -c
numberfiles=$(ls -m | wc -w )

echo " files in these folder are $files "
if [ ! -d $dir ]; then
mkdir Copy
else
echo " $dir exists so now will copy files "
fi

while [ $counter -lt $numberfies ];
do
cp ${file}s ${dir}
let counter=counter+1
until [ $counter=numberfiles ] do
shift 1

#cp $files $dir/$files
#echo " $files has been copied "

grail · 11-21-2011, 06:37 PM

Is this homework? Neither of your loops are terminated and this appears to be the really long way to do this. You also make assumptions that you are in the correct
directory when executing it.

Maybe answer some of the above first as I do not wish to send you on a different angle if you are trying to learn some of the above concepts first.

me. · 11-22-2011, 01:51 AM

hi gral,

yes it is for my home network,
these loops are not terminated I know I just come up with ideas which doesnt work,
but I think you understand what I am trying to achieve and hopefully you can give me solution, an easy, short solution.

I want copy file by file and have it displayed...

salemhouda · 11-22-2011, 03:06 AM

In the end of the loop you miss done.

Code:

while [ condition ]
do
   command1
   command2
   command3
done

Code:

  #!/bin/bash 
         COUNTER=20
         until [  $COUNTER -lt 10 ]; do
             echo COUNTER $COUNTER
             let COUNTER-=1
         done

David the H. · 11-23-2011, 07:10 AM

Code:

files=$(pwd | ls -m )

Um, what? Trying to pipe the output of pwd into ls? ls doesn't read from stdin, so this is pointless. Oh, and since the -m option adds a comma to each entry, any subsequent command that tries to read the name will probably fail to find it. Perhaps you want ls "$PWD" instead?

But in any case, this isn't a good way to go about it. first of all, Parsing ls for filenames is generally a bad idea. Try using simple globs instead. Second, when working on lists. you should be storing them in arrays rather than scalar variables.

Since arrays are indexed by number, it also becomes much easier to count and track them without the need for external tools like wc.

Code:

cp ${file}s ${dir}

${file}s simply takes the undefined variable "file" and adds "s" to it, so you get the output "s". I'm assuming this is a typo?

But in addition, always quote your variable expansions, unless you want word-splitting to occur. It's vital in scripting to understand exactly how the shell handles arguments and whitespace:
http://mywiki.wooledge.org/Arguments
http://mywiki.wooledge.org/WordSplitting
http://mywiki.wooledge.org/Quotes

Although as written, your script actually depends on the variable "files" being word-split so that cp can grab the individual filenames. The first name with a space in it is going to mess it up. Again, use an array instead.

Finally, learn the value of clear formatting and commenting. Lining things up in neat blocks would help you notice and avoid simple syntax problems like missing terminators.

Edit: One more.

Code:

until [ $counter=numberfiles ] do

Check out bash pitfalls 4, 7, and 10 to understand what's wrong here.

http://mywiki.wooledge.org/BashPitfalls