BASH script question

Hi,

I want to create a script that gets a filename as an argument.
The script should generate a listing in long list format of the current directory, sorted by file size.
This list must be written to a new file by the filename given on the command line.

Can someone help me with this?

Here is my start:

#!/bin/sh
echo "Please give in the filename"
read NEW_FILENAME
#read the current directory in long listing and sort by filesize (small to big) and writes it to the given filename
ls -l -S -r  > $NEW_FILENAME 

But I am kind of stuck.

Thanks for your help so far.

Hi
You can simple use this command, to obtain the list of extant files and directories sorted by size

ls -al | sort +4 -r > temp.log

If your OS is HP-UX, you can use:

 ll | sort +4 -r > temp.log

Regards

Hi,

I think I allready found the solution ...

#!/bin/sh
echo "Please give in the filename"
read NEW_FILENAME
#read the current directory in long listing and sort by filesize (small to big) and writes it to the given filename
ls -l -S -r  > $NEW_FILENAME

Glad you found but is you want your script to be a bash script it have to start with:
#!/bin/bash

I am a n00b when it comes to shell scripting ... but this is one of the things you cant miss when you read teh guides and books on this subject

Hi,

To add a command line arguement to a script try:

listit.sh

#!/bin/sh
if test $# -gt 0; then
target=$1;
else
echo "no output file specified using default.lst"
target=default.lst
fi
ls -l -S -r > $target

You can then run
./listit.sh myfile.lst

If you just run the script without an argument it will use the default.lst file.

If you want this to behave more like a standard unix command line tool, you might want to consider using getopts. For example:

#!/bin/bash

usage() {
cat <<EOT
Usage: `basename $0` [-f] [-o filename]

    -o file  output to filename.  Default: prompt for filename
    -f       force overwrite if output file already exist
EOT
}

filename=""
force=false
while getopts fo: opt; do
  case "$opt" in
    o) filename="$OPTARG" ;;
    f) force=true ;;
  esac
done
shift `expr $OPTIND - 1`

if [ -z "$filename" ]; then
  read -p "Enter a filename: " filename
fi

if [ -s "$filename" -a $force = "false" ]; then
  echo "ERROR: $filename exists" >&2
  exit 1
fi

ls -lSr > "$filename"