Jeff Jonas'
UNIGROUP presentations
Followups to previous Unigroup presentations:
Thursday 19-July-2012
quick Hope #9 report
Thursday 15-September-2011
upcoming events & a little Unix history
Thursday 18-Nov-2010
On Thursday 18-Nov-2010, Rob Weiner and I (Jeffrey Jonas)
led a lively discussion of Unix/Linux Command Line Tips & Tricks.
MANY THANKS to the enthusiastic participation of our knowledgeable audience, particulalry
- Robert Quiles for his hardware knowledge of CD/DVD media & burners
- Chris Lent and Mike Smith for knowing amazing Linux & shell details
evil USB cards
Here's a new security risk: USB cards that totally bypass any security measures such as
virus scans or disabling auto-play.
See also:
Plug and Prey: Malicious USB Devices Presented at Shmoocon 2011 by Adrian Crenshaw
Click here for my notes about shell programming (Stupid Unix Tricks)
and rants about things such as hard vs. symbolic links.
In particular,
my bashrc has many clever functions for usual and unusual circumstances.
Here are some of my shell and Perl scripts.
I'm somewhat embarassed by never re-writing them to production code,
but they work and help me every day.
- dup7 is a Perl script that finds duplicate files regardless of name.
It's far from optimized but it works!
Anything with my initials "jsj", zzz or !!! is for debugging
- lnn is how I create hard links among files dup7 found to be duplicates.
It's a clever shell script for handling filenames with whitespace.
- cmpp is a Perl script for verifying "are all files in A also in B?".
The args are 2 directories, which are recursively traversed for all regular files.
It's intentionally asymmetric since it's common to have a subset of the files for distribution or sharing.
- grepall is a shell script that greps for a string by traversing a tree of files (uses "find")
It only prints the names of the files containing the regex.
- res (for RESize) uses "convert" to create thumbnails for all the image files listed,
and creates a "thumbs.html" with the bare HTML to use the thumbnails as a link to the fill size image.
- catch uses ttcp to receive a file over the network with less overhead than ftp
and without any listener (such as
inetd,
xinetd) or NFS setup.
The sending side needs a compatible version of ttcp (particulary the same port number).
To use: run "catch" on the receiving side, then on any other machine run something like:
tar czf - . | ttcp -t receiving_hostname
This pipeline transmits a tar (or other archive)
directly over the network without intermediate files.
- rescan-scsi-bus.sh is from the Internet: rescans the SCSI bus without rebooting.
- ttcp, minicom and dd_rescue are utilities from the Internet.