Table of Contents
Unix/Linux Keyword 1
Version Control
Definition
Version control refers to managing the changes in a document, source code, or other collection of information. The changes are usually documented by a revision number, timestamp, and who made the change. Revisions can then be compared with or restored to a previous revision. Version control uses a repository, which stores both the current and previous data of the files being version controlled. Version control repositories can either be local only, client-server, or distributed.
Local only repositories are outdated and obsolete. In a local only system, all users must share the same computer system. In a client-server version control system, users share a single repository. While not as outdated or obsolete as a local only repository, it is still not the optimal choice. A distributed revision control system (DRCS) creates a peer-to-peer network, where each user has their own local repository. Changes are then shared between repositories. One of the biggest upsides to a DRCS is that it does not rely on a central node, and therefore is more durable. Two of the most popular DRCS's are Mercurial and Git.
References
- Reference 1: http://en.wikipedia.org/wiki/Revision_control
Unix Keyword Phase 2
File Compression.
Definition
involves encoding information using fewer bits than the original file. It helps reduce resources usage such as data storage space or transmission capacity. In order to use the data again though you must uncompress the file.
References
List any sites, books, or sources utilized when researching information on this topic. (Remove any filler text).
- Reference 1
- Reference 2
- Reference 3
unix Keyword 1 Phase 2 Phase 2
File Compression
Definition
File compression is the reduction in file size by encoding the file using fewer bits than the original file. This can be done by eliminating redundancies in the file (lossless compression), or by identifying and removing marginally important data (lossy compression).
References
Demonstration
To demonstrate the file compression, I first created a regular ASCII text file. The original filesize was 1.4kb (Containing a glorious rap I wrote about file compression, which was mostly rambling). Then, to demonstrate how compression works, I used the command “gzip -9 compression.txt” to compress the file with the maximum compression. The output of this was a new file titled compression.txt.gz, which now had a size of 729 bytes (approximately 50% compression).
lab46:~/Compression Demonstration$ ls -lh total 4.0K -rw-r--r-- 1 smeas lab46 1.4K Sep 28 01:36 compression.txt lab46:~/Compression Demonstration$ gzip -9 compression.txt lab46:~/Compression Demonstration$ ls -lh total 4.0K -rw-r--r-- 1 smeas lab46 729 Sep 28 01:36 compression.txt.gz lab46:~/Compression Demonstration$