Commands by uberbaud (1)

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Calculate days on which Friday the 13th occurs (inspired from the work of the user justsomeguy)
Friday is the 5th day of the week, monday is the 1st. Output may be affected by locale.

Rename files in batch

grep for minus (-) sign
Use flag "--" to stop switch parsing

Update a namecheap @ A record to point to your current internet-facing IP address
Sets the @ A record for your domain hosted by namecheap to your current internet-facing IP address, logs success or failure with syslog, and logs the data returned to /root/dnsupdate. Change the XXX's as appropriate. More info at: http://www.namecheap.com/support/knowledgebase/article.aspx/29/

clone directory structure
dir1 and all its subdirs and subdirs of subdirs ... but *no files* will be copied to dir2 (not even symbolic links of files will be made). To preserve ownerships & permissions: $ cp -Rps dir1 dir2 Yes, you can do it with $ rsync -a --include '*/' --exclude '*' /path/to/source /path/to/dest too, but I didn't test if this can handle attributes correctly (experiment rsync command yourself with --dry-run switch to avoid harming your file system) You must be in the parent directory of dir1 while executing this command (place dir2 where you will), else soft links of files in dir2 will be made. I couldn't find how to avoid this "limitation" (yet). Playing with recursive unlink command loop maybe? PS. Bash will complain, but the job will be done.

useful tail on /var/log to avoid old logs or/and gzipped files
with discard wilcards in bash you can "tail" newer logs files to see what happen, any error, info, warn...

Using a single sudo to run multiple && arguments
This will also work with bash instead of sh shell sudo bash -c 'apt update -y && apt upgrade -y'

send raw data (hex written)using UDP to an IP and port
Use it to send raw data to a networked device. Used to interact with relay controller board whose documentation is lost, so use wireshark to sniff the sent data and replayed using the command.

Watch the progress of 'dd'
Only slightly different than previous commands. The benefit is that your "watch" should die when the dd command has completed. (Of course this would depend on /proc being available)

connect via ssh using mac address
Connect to a machine running ssh using mac address by using the "arp" command


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