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post(gnu-busybox): limitation of gunzip

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@ -2,7 +2,7 @@
title: GNU vs BusyBox Unix tools title: GNU vs BusyBox Unix tools
excerpt: Alpine uses BusyBox while Ubuntu uses GNU tools, and they behave differently. excerpt: Alpine uses BusyBox while Ubuntu uses GNU tools, and they behave differently.
date: 2018-10-13 date: 2018-10-13
updated: 2018-10-31 updated: 2021-04-19
tags: tags:
- linux - linux
- alpine - alpine
@ -19,9 +19,9 @@ I use it in my [urlhaus-filter](https://gitlab.com/curben/urlhaus-filter) repo t
## Exit with code 1 ## Exit with code 1
I was dismayed by those [error messages](https://gitlab.com/curben/urlhaus-filter/-/jobs), I tested the scripts on my workstation! Looking through error message, I noticed the Alpine's Unix tools behave differently than mine. I investigated further by running an Alpine live cd. While setting up GitLab CI for urlhaus-filter, I encountered many issues despite tested fine on my workstation. Sifting through the error messages, I noticed the Alpine's Unix tools behave differently than mine. I investigated further by testing the script on an Alpine VM.
I `--version` those tools (only those I use in the [scripts](https://gitlab.com/curben/urlhaus-filter/tree/master/utils)) and the output is totally different! The Alpine tools output `BusyBox vXX`, which shows they are part of BusyBox. I briefly read up the [wiki](https://en.wikipedia.org/wiki/BusyBox#Features) and noticed the following line, I compared the `--version` of those tools in Ubuntu and Alpine, and noticed the outputs are totally different. The Alpine tools output `BusyBox vXX`, which shows they are part of BusyBox. I briefly read up the [wiki](https://en.wikipedia.org/wiki/BusyBox#Features) and noticed the following line,
{% blockquote %} {% blockquote %}
...compared GNU, BusyBox, asmutils and Perl implementations of the standard Unix commands... ...compared GNU, BusyBox, asmutils and Perl implementations of the standard Unix commands...
@ -41,14 +41,14 @@ Programs included in BusyBox can be run simply by adding their name as an argume
after /bin/ls is linked to /bin/busybox after /bin/ls is linked to /bin/busybox
{% endblockquote %} {% endblockquote %}
So, Alpine uses BusyBox and Ubuntu uses GNU. While Ubuntu also bundles with BusyBox, but it uses GNU by default. So, Alpine uses BusyBox and Ubuntu uses GNU. Ubuntu does include BusyBox by default, but it mostly uses GNU.
## List ## List
I tested the tools on Alpine and Ubuntu, and noted their behaviour. BusyBox = BB. I tested the tools on Alpine and Ubuntu, and noted their behaviour. BusyBox = BB.
- **gzip/gunzip/zcat**: BB only support gzip/bzip2/xz format, not the ubiquitous zip. To extract, use **unzip**. GNU supports zip, but its zcat can only extract the first file. Use bsdtar to extract all files. - **gzip/gunzip/zcat**: BB only support gzip/bzip2/xz format, not the ubiquitous zip. GNU can only extract the first file. Use unzip or bsdtar to extract all files.
- **unzip**: GNU doesn't support stdin as input. Use funzip to decompress stdin, but only extract the first file like zcat. BB support stdin and extract all files, through `unzip -`. - **unzip**: GNU doesn't support stdin as input. funzip can decompress from stdin, but only the first file (like zcat). BB support stdin and extract all files, through `unzip -`.
- **sed**: BB doesn't support -z argument which is used to find/replace \n new line character. A [workaround](https://stackoverflow.com/a/1252191) is `sed ':a;N;$!ba;s/\n/<new character>/g' file` or `sed -e ':a' -e 'N' -e '$!ba' -e 's/\n/<new character>/g' file`. GNU `sed -z 's/\n/<new character>/g' ` works. - **sed**: BB doesn't support -z argument which is used to find/replace \n new line character. A [workaround](https://stackoverflow.com/a/1252191) is `sed ':a;N;$!ba;s/\n/<new character>/g' file` or `sed -e ':a' -e 'N' -e '$!ba' -e 's/\n/<new character>/g' file`. GNU `sed -z 's/\n/<new character>/g' ` works.
- **bsdtar**: Since GNU's zcat and funzip can only extract the first file, in addition to BB's unzip, another alternative is bsdtar. bsdtar can be installed through `libarchive-tools` package. To extract zip from stdin, use `$ bsdtar -xf -`. - **bsdtar**: Since GNU can only extract the first file, in addition to BB's unzip, another alternative is bsdtar. bsdtar is available through `libarchive-tools` package. To extract zip from stdin, use `$ bsdtar -xf -`.
- **patch**: BB doesn't support `--backup` option. BSD doesn't support `--verbose` option. - **patch**: BB doesn't support `--backup` option. BSD doesn't support `--verbose` option.