gzip
Linux Command – gzip ใช้ในการบีบอัดข้อมูล file หรือ การ zip file
คำสั่ง
ตังอย่าง file data
$ ls -ltr data -rw-r--r-- 1 root root 11421 May 8 15:07 data
1. ทำการ zip file ข้อมูล
gzip <file>
$ gzip data $ ls -ltr data* -rw-r--r-- 1 root root 5084 May 8 15:07 data.gz
2. ทำการ zip file ข้อมูลโดยระบุระดับการบีบอัด
gzip -<1-9> <file>
$ gzip -9 data $ ls -ltr data* -rw-r--r-- 1 root root 5084 May 8 15:07 data.gz
3. ทำการ unzip file ข้อมูล
gzip -d <file>
$ gzip -d data.gz $ ls -ltr data* -rw-r--r-- 1 root root 11421 May 8 15:07 data
4. ทำการ zip file ข้อมูลโดยการเขียน file ใหม่
gzip -c <file> > <newfile>
$ ls -ltr data* -rw-r--r-- 1 root root 11421 May 8 15:07 data $ gzip -c data > data.gz $ ls -ltr data* -rw-r--r-- 1 root root 11421 May 8 15:07 data -rw-rw-r-- 1 root root 5084 May 8 15:16 data.gz
5. ตรวจสอบสถานะการบีบอัด หรือ zip file
gzip -l <file>
$ gzip -l data.gz compressed uncompressed ratio uncompressed_name 5084 11421 55.7% data
โครงสร้างคำสั่ง
gzip [ -acdfhklLnNrtvV19 ] [--rsyncable] [-S suffix] [ name ... ]
gunzip [ -acfhklLnNrtvV ] [-S suffix] [ name ... ]
zcat [ -fhLV ] [ name ... ]
รายละเอียด
เป็นคำสั่งที่ใช้ในการบีบอัดข้อมูล file หรือ การ zip file โดยจะช่วยลดขนาดของ file ลงตามระดับที่กำหนดในการบีบอัดข้อมูล file ที่ได้จะเป็นนามสกุล .gz
Option
-a --ascii Ascii text mode: convert end-of-lines using local conventions. This option is supported only on some non-Unix systems. For MSDOS, CR LF is converted to LF when compressing, and LF is converted to CR LF when decompressing. -c --stdout --to-stdout Write output on standard output; keep original files unchanged. If there are several input files, the output consists of a sequence of independently compressed members. To obtain better compression, concatenate all input files before compressing them. -d --decompress --uncompress Decompress. -f --force Force compression or decompression even if the file has multiple links or the corresponding file already exists, or if the compressed data is read from or written to a ter‐ minal. If the input data is not in a format recognized by gzip, and if the option --stdout is also given, copy the input data without change to the standard output: let zcat behave as cat. If -f is not given, and when not running in the background, gzip prompts to verify whether an existing file should be overwritten. -h --help Display a help screen and quit. -k --keep Keep (don't delete) input files during compression or decompression. -l --list For each compressed file, list the following fields: compressed size: size of the compressed file uncompressed size: size of the uncompressed file ratio: compression ratio (0.0% if unknown) uncompressed_name: name of the uncompressed file The uncompressed size is given as -1 for files not in gzip format, such as compressed .Z files. To get the uncompressed size for such a file, you can use: zcat file.Z | wc -c In combination with the --verbose option, the following fields are also displayed: method: compression method crc: the 32-bit CRC of the uncompressed data date & time: time stamp for the uncompressed file The compression methods currently supported are deflate, compress, lzh (SCO compress -H) and pack. The crc is given as ffffffff for a file not in gzip format. With --name, the uncompressed name, date and time are those stored within the compress file if present. With --verbose, the size totals and compression ratio for all files is also displayed, unless some sizes are unknown. With --quiet, the title and totals lines are not dis‐ played. -L --license Display the gzip license and quit. -n --no-name When compressing, do not save the original file name and time stamp by default. (The original name is always saved if the name had to be truncated.) When decompressing, do not restore the original file name if present (remove only the gzip suffix from the compressed file name) and do not restore the original time stamp if present (copy it from the compressed file). This option is the default when decompressing. -N --name When compressing, always save the original file name and time stamp; this is the default. When decompressing, restore the original file name and time stamp if present. This option is useful on systems which have a limit on file name length or when the time stamp has been lost after a file transfer. -q --quiet Suppress all warnings. -r --recursive Travel the directory structure recursively. If any of the file names specified on the command line are directories, gzip will descend into the directory and compress all the files it finds there (or decompress them in the case of gunzip ). --rsyncable While compressing, synchronize the output occasionally based on the input. This increases size by less than 1 percent most cases, but means that the rsync(1) program can take advantage of similarities in the uncompressed input when synchronizing two files compressed with this flag. gunzip cannot tell the difference between a compressed file created with this option, and one created without it. -S .suf --suffix .suf When compressing, use suffix .suf instead of .gz. Any non-empty suffix can be given, but suffixes other than .z and .gz should be avoided to avoid confusion when files are transferred to other systems. When decompressing, add .suf to the beginning of the list of suffixes to try, when deriving an output file name from an input file name. -t --test Test. Check the compressed file integrity. -v --verbose Verbose. Display the name and percentage reduction for each file compressed or decompressed. -V --version Version. Display the version number and compilation options then quit. -# --fast --best Regulate the speed of compression using the specified digit #, where -1 or --fast indicates the fastest compression method (less compression) and -9 or --best indicates the slowest compression method (best compression). The default compression level is -6 (that is, biased towards high compression at expense of speed).
กลุ่มคำสั่ง
znew(1), zcmp(1), zmore(1), zforce(1), gzexe(1), zip(1), unzip(1), compress(1)
Reference:
Author: Suphakit Annoppornchai
Credit: https://saixiii.com
