Application Usage

This page covers usage instructions for specific applications.

MP3Gain

$ find ~/Music/ -iname "*.mp3" -exec mp3gain -r -d 6 -c {} \;"
The command above will recursively search through the directory Music and all its sub-directories and apply Replay Gain to all found mp3-files. This command is useful to batch process a whole music collection. If the command is repeated a second time for the same directory, only new files with different sound volume levels will be processed.

This example applies Replay Gain for each file separately. It is also possible to to process a whole album of songs and keep the variations of sound strength within the album. You can process a single file, specify the target volume and a whole bunch of other options. Read more at the MP3Gain home page.

rsync

Simple local usage, between mounted file systems:
$ rsync -a --delete --progress /source/path /destination/path >> ~/.rsynclog

Simple ssh usage, over ssh network connection:
$ rsync -a --delete --progress -e ssh /source/path remoteuser@remotehost:/backup/path 2>&1 | tee -a ~/.rsynclog

Explanations of options:

-a Preserves attributes and requires root to do the sync. It is a combined way of passing the options -rlptgoD (recursive, links, permissions, times, group, owner, devices).

-rlpt Alternative for backup as normal user. Preserves user attributes (recursive, links, permissions, times).

--delete Sync deleted files. Files missing on /source/path (most likely deleted), but existing on /destination/path, will be deleted on /destination/path.

--progres Show progress during syncronisation.

-e Use ssh (ssh usage is not covered here).

To append the standard output from rsync as new lines in a file instead of displaying it in the terminal, add suffix: >> ~/.rsynclog

To append standard output as well as standard errors to a file and also display it in the terminal, instead use the following suffix: 2>&1 | tee -a ~/.rsynclog

Another usage for rsync is to read a .m3u playlist and copy the linked music to a directory with the same name in your home directory. Use the command below:
$ cd / && rsync --ignore-existing --progress --stats --no-relative --no-dirs --files-from=$HOME/Music/Playlists/example.m3u / $HOME/example

Visit the Arch Linux rsync wiki page for detailed instructions.

unison

Simple usage: $ unison path1 path2

The command above will sync path1 with path2 . Any differences will be detected and the user will be asked what to do.
For differences where unison can propose a default action f you only have to press enter to accept. For differences where the same file is modified on both paths unison will not propose an action ? . In this case input > to keep the change in path1 and sync it to path2 or input < to do the oposite.

To automatically accept proposed default actions f in order to speed up syncronization, use the following syntax: $ unison path1 path2 -auto

Unison has a rich set of features and can sync directly between machines, e.g with ssh, when installed on both machines, without having to mount any remote directory.

Visit the Arch Linux unison wiki page for detailed instructions.

VirtualBox

virtualbox is the name of the free Open Source version of VirtualBox. There are also some proprietary extensions (free for personal use but needs a license for commercial use) to add additional features.

For documentation, visit the Ubuntu VirtualBox community page.

In order to use VirtualBox, add your user to the group vboxusers:
# gpasswd -a USERNAME vboxusers

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