what is the difference between commands compress, pack and gzip


 
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# 1  
Old 09-24-2011
what is the difference between commands compress, pack and gzip

Are the above commands does the same job ?

same functionaliy ?

If so, why do we have three utilities for the same functinality.
# 2  
Old 09-24-2011
Yes in some ways they are the same functionality they intend to compress data.
Some do better than others e.g gzip is better than compress and pack in overall .

compress and gzip are alike in some ways as they are exploit the same algorithm but they differ in some ways.

compress : The compress utility will attempt to reduce the size of the named files by using adaptive Lempel-Ziv coding. Typically, text such as source code or English is reduced by 50-60%. Compression is generally much better than that achieved by Huffman coding (as used in pack ).

pack : The pack command attempts to store the specified files in a compressed form. Wherever possible (and useful), each input file file is replaced by a packed file file.z with the same access modes, access and modified dates, and owner as those of file. If pack is successful, file will be removed.

gzip Is a GNU version of Lempel-Ziv coding (LZ77) which reduces the size of the named files using Lempel-Ziv coding (LZ77). Whenever possible, each file is replaced by one with the extension ‘.gz’, while keeping the same ownership modes, access and modification times.
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