Commands by mathias (5)

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Sync MySQL Servers via secure SSH-tunnel
I wanted to keep a backup of my company database server on my local homeserver. After I found maatkit to sync databases, everything except security seemed fine. SSH takes care of that part.

Python version 3: Serve current directory tree at http://$HOSTNAME:8000/
In Python version 3, the module was merged into http.server. Gentlemen, change your aliases.

copies 20 most recently downloaded mp3 files (such as from Miro) into a directory
Change ~/tmp to the destination directory, such as your mounted media. Change -n20 to whatever number of files to copy. It should quit when media is full. I use this to put my most recently downloaded podcasts onto my phone.

View Owner, Group & Permissions.
#Alias alias perm="stat -c '%n %U:%G-%a'" #Function perm() { for ll in $@; do stat -c "%n %U:%G-%a" "$ll"; done; }

Print number of mb of free ram

Show complete URL in netstat output
The -W switch of netstat makes it print complete URL of the connections, which otherwise by default is truncated to fit its default column size. Now to compensate for irregular column sizes, pipe the output to column (-t switch of column prints in tabular form). The only downside to this part is that the very first row, the header, goes pear shape.

using tee to echo to a system file with sudo privileges
We sometimes need to change kernel parameters by echoing the file . This needs root privilege and if we do it using sudo like this , it fails $ sudo echo ondemand > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor -bash: /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor: Permission denied We can achieve this with the tee command by just doing sudo without logging as root user http://www.zaman4linux.in/2010/09/using-tee-to-echo-to-system-file-with.html

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

output your microphone to a remote computer's speaker
This will output the sound from your microphone port to the ssh target computer's speaker port. The sound quality is very bad, so you will hear a lot of hissing.

rsync over ssh using alternative port number
Useful, when you need to backup/copy/sync a folder over ssh with a non standard port number


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