Have a shell script check for a file to exist before processing another file

Shell Programming and Scripting
1

I have a shell script that runs all the time looking for a certain type of file and then it processes the file through a series of other scripts. The script is watching a directory that has files uploaded to it via SFTP. It already checks the size of the file to make sure that it is not still uploading before it starts processing. I would like to place another check in the script that looks for the existance of another file before processing begins. The script looks like:

#!/bin/ksh
PATH=/gers/nurev/menu/pub/sbin:/gers/nurev/menu/pub/bin:/gers/nurev/menu/pub/mac
:/gers/nurev/menu/adm/sbin:/gers/nurev/menu/adm/bin:/gers/nurev/menu/adm/mac:/ge
rs/nurev/custom:/gers/nurev/fix:/gers/nurev/src_rev/fix:/gers/nurev/opt/path:/ge
rs/nurev/bin:/g/bin:/usr/bin:/etc:/usr/sbin:/usr/ucb:/sbin:.
ORACLE_HOME=/gers/nurev
ORACLE_SID=nurev
export PATH
export ORACLE_HOME
export ORACLE_SID
 
#
# Function : is_file_arrived file
# Arg(s)   : file = file to verify
# Output   : None
# Status   : 0 = yes file arrived, 1 = no
# Env.     : IFA_WAIT : interval (secs) for file size check (def=5)
#
 
is_file_arrived() {
   [ -z "$1" ] && return 1
   local file=$1
   local arrived=1
   local size1 size2
   if [ -f "$file" -a -z "$(fuser $file 2> /dev/null)" ] ; then
      size1=$(ls -l $file 2>/dev/null | awk '{print $5}')
      sleep ${IFA_WAIT:-15}
      size2=$(ls -l $file 2>/dev/null | awk '{print $5}')
      [ ${size1:-1} -eq ${size2:-2} ] && arrived=0
   fi
   return $arrived
}
 
 
processFile ()
{
   local fileName=$1
   local fileExtension=$2
   local fileNewName="/gers/nurev/datafiles/str${fileExtension}.asc"
   local filePrintPath="/gers/nurev/print"
   local fileTmpPath="/gers/nurev/tmp"
   local fileODIName="str${fileExtension}.pos"
   mv -Eignore $fileName $fileNewName     
   prepup $fileNewName $fileExtension
   mv -Eignore  $filePrintPath/$fileODIName $fileTmpPath/$fileODIName
   save2tmp $fileExtension
   call_siu $fileExtension
}
 
# Main Processing
 
nsec=1
while [[ "$(date +%H%M)" -lt 2329 ]]
do
   for fileName in /gers/nurev/datafiles/[Uu][Pp][Ll][Oo][Aa][Dd].[0-9][0-9][0-9
][0-9]
   do
      fileExtension=${fileName#*.}
      is_file_arrived "$fileName" && nsec=1 && processFile $fileName $fileExtension
   done
   sleep $nsec
   case $nsec in
      1)   nsec=15;;
      15)  nsec=45;;
      45)  nsec=90;;
      90)  nsec=300;;
      300) nsec=600;;
      600) nsec=900;;
      *)   nsec=1800;;
   esac
done

...I'd like to check for a file in /gers/genret/tmp/poll_####.txt (where "####" is the $fileExtension variable. I think the file check should be in the "Main Processing" section before it sends to the file to the "is_file_arrived" function? I'f there is a "poll_####.txt" file present I would just like the script to move onto the next file and look at it again later. This would prevent two files of the same type processing at the same time. I'm thinking something like a "if-then"?

2

You can do something like this:

   for fileName in /gers/nurev/datafiles/[Uu][Pp][Ll][Oo][Aa][Dd].[0-9][0-9][0-9
][0-9]
   do
      fileExtension=${fileName#*.}
      [[ -a /gers/genret/tmp/poll_$fileExtension.txt  ]] && continue
      is_file_arrived "$fileName" && nsec=1 &&       processFile $fileName $fileExtension
   done

Jean-Pierre.

3

Forgive my ignorance, so how would bracketing the "-a" work?

[[ -a /gers/genret/tmp/poll_$fileExtension.txt  ]] && continue

...it would check for the file "poll_" and if it found it stop there and move onto the next file? I'm confused how this works?

4

The following code is equivalent :

if [[ -a /gers/genret/tmp/poll_$fileExtension.txt  ]]
then
   continue
fi

If the file pooll_ exists, then resume the next iteration of the for loop (proceed next file).

Jean-Pierre.