Shell Programming and Scripting

#!/usr/bin/bash
# $1=filename of file with the list of files to copy
# $2=column header for col in list file with filenames (filePath in most cases)
# $3=src dir
# $3=destination dir

FILE_LIST="$1"
FILE_FIELD="$2"
SOURCE_DIR="$3"
DEST_DIR="$4"

if [ $# -ne 4 ]
then
   echo "usage: $0 file_list field src_dir dest_dir" >&2
   exit 1
fi
if [ ! -f "$FILE_LIST" ]
then
    echo "Invalid filelist $FILE_LIST">&2
    exit 2
fi
# create destination directory if it doesnt' exist
if [ ! -d "$DEST_DIR" ]
then
    mkdir $DEST_DIR
fi
if [ ! -d "$SOURCE_DIR" ]
then
    echo "Invalid source directory">&2
    exit 4
fi
 
awk -vS="$SOURCE_DIR" -vFLD="$FILE_FIELD" 'NR==1{for(i=1;i<=NF;i++)if($i==FLD)w=i;next}
w {print S "/" $w}' $FILE_LIST | xargs  -r cp --target-directory="$DEST_DIR"

awk -vS="$SOURCE_DIR" -vFLD="$FILE_FIELD" -v qq='"' 'NR==1{for(i=1;i<=NF;i++)if($i==FLD)w=i;next} w {print qq S "/" $w qq}' $FILE_LIST | xargs  -r cp --target-directory="$DEST_DIR"