linux:basics
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linux:basics [2019/08/14 11:30] mstraub [Date & Time] |
linux:basics [2020/12/21 09:51] (current) mstraub proper switch for ISO 8601 |
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| ==== Compressing files ==== | ==== Compressing files ==== | ||
| - | For compressig files the zip formats gzip (.gz) and bzip2 (.bz2) are commonly used - especially the former. | + | For compressing files the zip formats gzip (.gz), bzip2 (.bz2) and xz (.xz, which uses LZMA compression) are commonly used. |
| + | |||
| + | Gzip is the most commonly used one, but according to [[https://www.rootusers.com/gzip-vs-bzip2-vs-xz-performance-comparison|this in-depth comparison]] .xz is the superior format - it is fast to decompress, achieves high compression rates and also has reasonable compression times until level 2 or 3. | ||
| + | |||
| + | The following commands (un)compress a single file and then remove the old (un)compressed file. | ||
| <code bash> | <code bash> | ||
| gzip my.txt # creates the gzipped file my.txt.gz and remove my.txt | gzip my.txt # creates the gzipped file my.txt.gz and remove my.txt | ||
| - | gzip -d my.txt.gz # recreates my.txt and removes my.txt.gz; same as gunzip | + | gunzip my.txt.gz # recreates my.txt and removes my.txt.gz; same as gzip -d |
| - | bzip2 my.txt # similar to gzip, but using bzip2 compression | + | |
| - | bzip2 -d my.txt.gz # similar to gunzip; same as bunzip2 | + | |
| </code> | </code> | ||
| - | All these commands (un)zip a single file and then remove the old (un)zipped file. | + | The commands ''bzip2'' + ''bunzip2'' and ''xz'' + ''unxz'' work in the same fashion. |
| + | For all zip formats there is a ''cat''-style alias which allows for the creation of an uncompressed data stream: | ||
| <code bash> | <code bash> | ||
| - | gunzip #unzip, same as gzip -d | + | zcat # stream uncompressed gzip file to stdout, same as gzip -cd |
| - | zcat #unzip to stdout, same as gzip -cd | + | bzcat |
| + | xzcat # same as xz --decompress --stdout | ||
| </code> | </code> | ||
| - | The programs ''gzip'' and ''bzip2'' have two "aliases": ''gunzip'' / ''bunzip2'' and ''zcat'' / ''bzcat''. These extra commands provide a short way to typically used functions. | + | |
| ==== Compressed Archives ==== | ==== Compressed Archives ==== | ||
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| <code bash> | <code bash> | ||
| date # default - a human readable format | date # default - a human readable format | ||
| - | date --rfc-3339=date # only the date - similar to ISO 8601 | + | date -I # only the date in ISO 8601 |
| - | date --rfc-3339=seconds # date and time - similar to ISO 8601 | + | date -Iseconds # date and time in ISO 8601 |
| date +%Y-%m-%dT%H%M # custom format useful for scripts, e.g. 2019-08-14T1129 | date +%Y-%m-%dT%H%M # custom format useful for scripts, e.g. 2019-08-14T1129 | ||
| </code> | </code> | ||
linux/basics.1565775014.txt.gz · Last modified: 2019/08/14 11:30 by mstraub
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