Monitor and ftp newly-added files on Linux -- modify existing code - bash

Question

The OS is centos 7, I have a small application to implement below functionality:
1.Read information from config.ini like this:
# Configuration file for ftpxml service
# Remote FTP server informations
ftpadress=1.2.3.4
username=test
password=test
# Local folders configuration
# folderA: folder for incomming files
folderA=/u02/dump
# folderB: Successfuly transfered files are copied here
folderB=/u02/dump_bak
# retrydir: when ftp upload fails, store failed files in this
# directory
retrydir=/u02/dump_retry
Monitor folder A. If there are any newly-added files in A, do step 3.
Ftp these new files to a remote ftp server in the order of their creation time, While upload finished, copy uploaded files to folder B and delete relevant files in folder A.
If ftp fails, store relevant files in retrydir and try to ftp them later.
Record every operation in a log file.
Detailed setting instruction for the application:
install ncftp package: yum install ncftp -y, it's not a service nor a daemon, just a client tool which is invoked in bash file for ftp purpose.
Customize these files to suit your setting using vi: config.ini
,ftpmon.path and ftpmon.service
copy ftpmon.path and ftpmon.service to /etc/systemd/system/, copy config.ini and ftpxml.sh to /u02/ftpxml/, run: chmod +x ftpxml.sh
Start the monitoring tool
sudo systemctl start ftpmon.path
If you want to enable it at boot time just enter: sudo systemctl enable ftpmon.path
Setup a cron task to purge queued files (add option -p)
*/5 * * * * /u02/ftpxml/ftpxml.sh -p
Now the application seems works well, except a special situation:
When we put several files in folder A continuously, for instance, put 1.txt, 2.txt and 3.txt...... one after another in a short time, we usually found 1.txt ftp well, but the upcoming files fails to ftp and still stay under folder A.
Now I am going to fix this problem. I suppose the error maybe due to: while doing ftp for the first file, maybe the second file is already created under folder A. so the code can't care about the second file.
Below is code of ftpxml.sh:
#!/bin/bash
# ! Please read the README.txt file !
# Copy files from upload dir to remote FTP then save them
# to folderB
# look our location
SCRIPT=$(readlink -f $0)
# Absolute path to this script
SCRIPTPATH=`dirname $SCRIPT`
PIDFILE=${SCRIPTPATH}/ftpmon_prog.lock
# load config.ini
if [ -f $SCRIPTPATH/config.ini ]; then
source $SCRIPTPATH/config.ini
else
echo "No config found. Exiting"
fi
# Lock to avoid multiple instances
if [ -f $PIDFILE ]; then
kill -0 $(cat $PIDFILE) 2> /dev/null
if [ $? == 0 ]; then
exit
fi
fi
# Store PID in lock file
echo $$ > $PIDFILE
# Parse cmdline arguments
while getopts ":ph" opt; do
case $opt in
p)
#we set the purge mode (cron mode)
purge_only=1
;;
\?|h)
echo "Help text"
exit 1
;;
esac
done
# declare usefull functions
# common logging function
function logmsg() {
LOGFILE=ftp_upload_`date +%Y%m%d`.log
echo $(date +%m-%d-%Y\ %H:%M:%S) $* >> $SCRIPTPATH/log/${LOGFILE}
}
# Upload to remote FTP
# we use ncftpput to batch silently
# $1 file to upload $2 return value placeholder
function upload() {
ncftpput -V -u $username -p $password $ftpadress /prog/ $1
return $?
}
function purge_retry() {
failed_files=$(ls -1 -rt ${retrydir}/*)
if [ -z $failed_files ]; then
return
fi
while read line
do
#upload ${retrydir}/$line
upload $line
if [ $? != 0 ]; then
# upload failed we exit
exit
fi
logmsg File $line Uploaded from ${retrydir}
mv $line $folderB
logmsg File $line Copyed from ${retrydir}
done <<< "$failed_files"
}
# first check out 'queue' directory
purge_retry
# if called from a cron task we are done
if [ $purge_only ]; then
rm -f $PIDFILE
exit 0
fi
# look in incoming dir
new_files=$(ls -1 -rt ${folderA}/*)
while read line
do
# launch upload
if [ Z$line == 'Z' ]; then
break
fi
#upload ${folderA}/$line
upload $line
if [ $? == 0 ]; then
logmsg File $line Uploaded from ${folderA}
else
# upload failed we cp to retry folder
echo upload failed
cp $line $retrydir
fi
# don't care upload successfull or failed, we ALWAYS move the file to folderB
mv $line $folderB
logmsg File $line Copyed from ${folderA}
done <<< "$new_files"
# clean exit
rm -f $PIDFILE
exit 0
below is content of ftpmon.path:
[Unit]
Description= Triggers the service that logs changes.
Documentation= man:systemd.path
[Path]
# Enter the path to monitor (/u02/dump)
PathModified=/u02/dump/
[Install]
WantedBy=multi-user.target
below is content of ftpmon.service:
[Unit]
Description= Starts File Upload monitoring
Documentation= man:systemd.service
[Service]
Type=oneshot
#Set here the user that ftpmxml.sh will run as
User=root
#Set the exact path to the script
ExecStart=/u02/ftpxml/ftpxml.sh
[Install]
WantedBy=default.target
Thanks in advance, hope any experts can give me some suggestion.

Answer 1

As you remove the successfull transfered files from A you can leave files with transfer errors in A. So I am dealing only with files in one folder.
List your files by creation time with
find -type f -maxdepth 1 -print0 | xargs -r0 stat -c %y\ %n | sort
if you want hidden files to be included or - if not -
find -type f -maxdepth 0 -print0 | xargs -r0 stat -c %y\ %n | sort
You'll get something like
2016-02-19 18:53:41.000000000 ./.dockerenv
2016-02-19 18:53:41.000000000 ./.dockerinit
2016-02-19 18:56:09.000000000 ./versions.txt
2016-02-19 19:01:44.000000000 ./test.sh
Now cut the filenames (or use xargs -r0 stat -c %n if it does not matter that the files are order by name instead the timestamp) and
do the transfer
check the success
move successfully transfered files to B
As you stated above, there are situations where newly stored files are not successfully transfered. This may be if the file is written further after you started the transfer. So filter the timestamp to be at least some time old. Add -mmin -1 to the find statement for "at least one minute old"
find -type f -maxdepth 0 -mmin -1 -print0 | xargs -r0 stat -c %n | sort
If you don't want to use a minute file age you'll have to check if the file is still open: lsof | grep ./testfile but this may have issues if you have tmpfs in your file system.
lsof | grep ./testfile
lsof: WARNING: can't stat() tmpfs file system /var/lib/docker/containers/8596cd310292a54652c7f50d7315c8390703b4816442146b340946779a72a40c/shm
Output information may be incomplete.
lsof: WARNING: can't stat() proc file system /run/docker/netns/fb9323486c44
Output information may be incomplete.
So add %s to the stats statement to check the file size twice within some seconds and if it's constant the file may be written complete. May, as the write process may be stalled.