Shell Programming and Scripting

Hi All,

I have 2 LINUX scripts (Lets say ScriptA & ScriptB) which copies files (lets say 'date_abc.txt , it goes to a while loop & checks for the files between 2 date varialbles) to directory X. (as Shown Below)

These 2 scripts are called from 2 different Autosys schedules & runs at the same time.(The above code piece is available in both scripts). I need to put a logic where it checks if one script already moved the file, the 2nd one shouldnt try to move it. (both the scripts moves the files to the same directory)

Any thoughts will be really helpful.

Thanks Much
Freddie

That sort of checking is going to be impossible to do 100% reliably. In the instant after checking a file, the other program may move it anyway.

I'd try to prevent the two code segments from running simultaneously instead. The mkfifo command will fail if the file already exists, so you can use it to check who gets there first:

Code:

while ! mkfifo /tmp/lock-fifo 2>/dev/null
do
        sleep 1
done

# Code segment you don't want programs to run at the same time

rm /tmp/lock-fifo

There's many other problems with your script as well:

Useless Use of Cat -- the shell is quite capable of reading files by itself.
Useless Use of Backticks -- using backticks on open-ended lists is an invitation to disaster.
Useless Use of ls *
Useless Use of grep | awk -- awk is an entire programming language which can do much more than 'print $5'. If you're using it, you might as well replace the pipe chain with it.

I'd rewrite it as so:

Code:

# Wait your turn
while ! mkfifo /tmp/lock-fifo 2>/dev/null
do
        sleep 1
done

trap "rm -f /tmp/lock-fifo 2>/dev/null" EXIT # Remove the fifo even if the program gets killed

while [ $enddate -gt $startdate ]
do
        enddate=`date -d "$enddate 1 day ago" "+%Y%m%d"`
        ls -l $COMMON_TMP | awk '($0 ~ ENDDATE) && /_abc[.]txt$/ { print $9 }' ENDDATE="$enddate"
done | while read FILENAME
do
        echo mv $FILENAME $COMMON_INBOX
        echo $FILENAME
done > $COMMON_TMP/filenames.txt

rm -f /tmp/lock-fifo

It may be possible to replace your entire loop with a single ls and a > < string comparison, if the date is in the filename itself.

Thanks for the below code suggestions. I am currently revisiting my code to put the fixes you provided.

Pls note that the dates are available in the filename itself. Can you pls let me know how to replace the entire loop with a single ls and a > < string comparison ?

Thanks Much Again,
Freddie

if files are 20120730_abc.txt then extract the date part and use math, rather than lots of calls to date and ls. this is for bash.

Code:

for f in "$COMMON_TMP"/*_abc.txt; do
        d=${f%%_*}
        (( d <= start && d >= end )) || continue
        mv "$f" "$COMMON_INBOX"
done