[EMAIL PROTECTED] wrote:
> .. Has Perl ever saved anyone's job? Their life?
Perl saved my code once (I claimed it as my life :)
This is an old post to the LAPM list but thought it might be interesting
to read...it's an interesting project, too...I should get back on it.
School-- really got in the way
'Tis all for now,
-Samy
-------- Original Message --------
Subject: LA.pm: how perl saved my life
Date: Sun, 14 Oct 2001 12:59:38 -0700
From: "Samy Kamkar [CommPort5]" <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]
Just about ten minutes ago, I screwed up. I was working on my
compression program (and I have a lot of it finished) and then something
just popped into my head that..something in HTML I wanted to try, so I
did. I opened up /webdir/other/tmp.html and played around for a bit
then when I was finished I wanted to get rid of it, so instead of rm
/webdir/other/tmp.html, I did rm tmp<TAB> (having bash complete the
file). Funny thing was, I wasn't in /webdir/other/, I was in the
compression code directory and I just happened to name the program
'tmpbzip'.
bash-2.03$ rm tmpbzip
Bang, I'm dead.
Now I knew the data was still somewhere on the partition, but wouldn't
be there for long since it would be overwritten very quickly. So I had
to think of something fast and didn't want to run any commands or
anything that would happen to overwrite that data in the partition. I
then su'd root for whatever I would need to do and then did a `df`:
su-2.03# df
Filesystem 1K-blocks Used Avail Capacity Mounted on
/dev/ad0s1a 49583 29898 15719 66% /
/dev/ad0s1f 1893575 1430752 311337 82% /usr
/dev/ad0s1e 19815 11976 6254 66% /var
procfs 4 4 0 100% /proc
The file I deleted happened to be on /usr, so I knew that partition was
/dev/ad0s1f.
The pressure was on, heart was beating *buh-boom..buh-boom*
I also remembered in the header of the program I was working on, a few
lines after #!/usr/bin/perl, I had the usage statement which went
something like: bzip [ -fvV123456...
And I also knew /var was on a different fs. This is good to know if I
need to write data anywhere because if I write something to /usr,
there's a big chance my data (program still in the filesystem) will be
overwritten.
So bam:
su-2.03# perl -e
'open(X,"/dev/ad0s1f");while(sysread(X,$x,4096)){if($l==1){print
$x}if($x=~/-fvV123/){$l=1;print $x;}}' > /var/data
.... a few minutes go by ...
Oct 14 12:31:49 LucidX /kernel: pid 7643 (perl), uid 0 on /var: file
system full
We found something!
I ^C and head /var/data:
su-2.03# head -n 30 /var/data
#!/usr/bin/perl
#
# bzip 0.1
#
# usage: bzip [ -fvV12345679 ] <file>
Perl saved my life.
Just thought this would be cool to share with all of you, just in case
any of you run into the same problem (I believ ext2 has some type of
recovery thing you can use but this was on FreeBSD)...
So simply, how the program works, so you all know....(here's a
nice-a-fied version, I wasn't looking for a clean program at the time :)
open(X, "</dev/ad0s1f"); # we open the partition for reading, the data
is still somewhere in it
while (sysread(X, $x, 4096)) { # we read 4096 bytes in a loop of the
partition
if ($l == 1) { # if $l was already set...
print $x; # let's get the data
}
if ($x =~ /-fvV123/) { # if our data contains the -fvV123 from the
usage...
$l = 1; # we'll set $l for reading after this
4096 bytes
print $x; # and we'll print what we have so far
}
}
Back to working on compression :)
-Samy
--
Samy Kamkar Pezeshkian -- [EMAIL PROTECTED]
LucidX.com / code.LucidX.com / LA.pm.org
