Question

I have a command that copies file from one dir to another

FILE_COLLECTOR_PATH="/var/www/";
FILE_BACKUP_PATH='/home/'
ls  $FILE_COLLECTOR_PATH | head -${1} |  xargs -i basename {} | xargs -t -i cp $FILE_COLLECTOR_PATH{} "${FILE_BACKUP_PATH}{}-`date +%F%H%M%S%N`"

I loop it in a shell script like,

#!/bin/sh
SLEEP=120
FILE_COLLECTOR_PATH="/var/www/";
FILE_BACKUP_PATH='/home/'
while true
do
ls  $FILE_COLLECTOR_PATH | head -${1} |  xargs -i basename {} | xargs -t -i cp $FILE_COLLECTOR_PATH{} "${FILE_BACKUP_PATH}{}-`date   +%F%H%M%S%N`"
 sleep ${SLEEP}
done

But it seems to move only 10 files and not all files in the dir, Why? It should suppose to move all files.

Answer 1

In general, don’t try to parse the output of ls in a script. You can end up with many different types of subtle problems. There is almost always a better tool for the job. Many times, this tool is find. For example, to generate a list of all of the files in a directory and do something to each of them, you would do something like this:

find <search directory> -maxdepth 1 -type f -print0 | xargs -0i basename {} ...

The -print0 and -0 arguments allow find and xargs to communicate filenames in a way that handles special characters (like spaces) correctly.

The find command has other options that you may find useful in a backup script (which is what it appears you are building). Options like -mmin and -newer will enable you to only back up files that have changed since the last iteration.