[ILUG] Slightly Off Topic : Concurrent Access to a Text File in a bash script - can I enforce thread safety

[Pádraig Brady]

Oisin Kim wrote:
> OK,
> 
> now that Pádraig has told me what I am looking for :)
> 
> I think the answer can be found at:
> 
> Basically, its not safe, as in my case, we will always be using NFS mounts.

So multiple systems will be writing to a central file over NFS.
You never said that :)
http://nfs.sourceforge.net/#faq_a9

> Thanks for all your help, I'll now benchmark lock files for this task,
> which should be fine :)
> Expect an update on the inode sorting next week.

Note to eliminate the possible NFS bottleneck from the equation
when comparing your parallel process version,
to my single process version, just compare the following
on a single machine:

time find . -maxdepth 1 -type f -printf "%i\t%f\n" |
sort -k1,1n |
cut -f2 |
tr '\n' '\0' |
xargs -r0 cksum >> log.file

for i in *.* do
   cksum $i >> log.file &
done
time wait 2>/dev/null

Pádraig.