Solved: Perl/NFS "Text File Busy" Error And Related Problems
I sent this through once, a day ago, and it didn't seem to get posted, so I'm
sending it again, since I think this could be quite helpful to anyone with a
similar problem (I found the problem posted several times on the web, but not
the solution!).
A good while back I searched Google and posted in a number of forums about a
problem I had with Perl. I am (and was) using 2 computers, both running
MEPIS Linux, which is Debian based, so this problem might happen with Debian
or other distros as well. On my workstation, I was using Kate, which is a
text editor with a console in the bottom of the window. Kate was on the
workstation, but in the console, I connect to my server, the system I'm
programming on, with ssh. That means I am actually editing the Perl file on
one computer (my workstation), by reading and writing through an NFS mounted
directory, and I am running it on another (my server).
The first problem I had was that when I saved my script through NFS, then
tried to run it, I always got this error message:
/usr/bin/perl: bad interpreter: Text file busy
It would last up to about 10 seconds, after which I could run the file. I
searched newsgroups on Usenet and mailing lists and general Google searches
for a problem like this. (After all, why use something like Perl if I had to
wait to run a program as if I were compiling?) I found a number of other
people had similar problems, and in some groups the given solution was simply
to wait 24 hours for NFS to make the file available to all. Since I found no
answer, I got used to waiting 10 seconds to run a script (and be thankful I
didn't have to wait 24 hours!).
Then, the other night, when I was exhausted, my eyes were blurry and I
literally almost could not focus on my monitor, I noticed another problem. I
was so exhausted I thought I was not paying attention or just missed
something, but this was a problem I had suspected before. Even though I
could barely stay awake, I forced myself to track what was going on and be
sure I wasn't imaging things. I was finally able to prove MY CHANGES IN MY
SCRIPTS DIDN'T ALWAYS SHOW UP WHEN I SAVED! The worksation would see
changes, but when I ran the program on the server, nothing was changed. I
finally would add an extra print statement to see what was going on -- and
change NOTHING else -- and not only did the program start printing out the
extra data, but it started working like it should with my change in it.
Now it is important to note these changes were in Perl modules. When I tried
to run a just edited Perl program, I'd get the "text file busy" error I
mentioned above. If the program used a module, and the module was just
edited, I would not get that error, so I could edit a module on the
workstation, save it to the NFS mount, run a program on the server that used
that module, and it would run.
However, sometimes the changes would not appear on the server when I ran it.
I finally figured out that the changes might be cached somewhere or not
synchronized yet. I don't if adding the 2nd change and saving again forced a
buffer to be written out, or if the changes in the modules were not getting
to the server for that same pesky 10 seconds it took for me to stop getting
the "text file busy" error, but the changes in the program did not show up
when first saved, and did later.
At this point I felt like I had gone down the rabbit hole and my LAN was going
to have to be renamed Wonderland, things seemed so strange. I *thought* the
problem was NFS, but wasn't even sure, at that point, what terms to use in
searching. With the kind help of some people in the Libranet-OT group at
Yahoo (not a Libranet group -- the Libranet OT group is made up of people
that got tired of the Libranet support list being censored and left
Libranet's list and the distro but wanted to continue their discussions) and
some people on the Debian Users list (through debian.org), I got some tips,
found out I was missing the program exportfs, posted that info, and finally
the saving grace, one short message that included a one line answer:
install nfs-kernel-server.
In Debian, that means running:
apt-get install nfs-kernel-server
as root. I did, and got errors as it tried to configure my /etc/exports file.
I had to edit my exports file a few times to make sure it worked. It turned
out my problem was only extra spaces. I won't go into the format of this
file, since that's posted in many other areas. I will say that my options
for each system were (rw,sync).
I don't know the name of the nfs-kernel-server package for RPM systems, but
basically, by making sure I had the rw,sync options set for each system
in /etc/exports, making sure the file was formatted properly, installing this
package, and, afterwards, running:
exportfs -ra
(which was probably already run when apt-get installed the package), I found
the frustrating "text file busy" error was gone.
Since I've seen this error in many posts, but never found an answer to it, I
thought I'd post this where I've asked for help, so others can find it via
Google and such in the future. I'm not an expert on NFS, and I really don't
know any other things to do to work with this problem other than what I've
posted. This is what fixed it for me. No more "text file busy" errors, and
no more Wonderland behavior of not updating saved files. If you're having
the same problem, I hope this fixes it . If it doesn't, I really can't tell
you what to try next, but I figure this info alone will help a good number of
people.
Hal
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