BusyBox是一個遵循GPL協議、以自由軟件形式發行的應用程序。
Busybox在單一的可執行文件中提供了精簡的Unix工具集，可運行於多款POSIX環境的操作系統，例如Linux（包括Android）、Hurd、FreeBSD等等。
由於BusyBox可執行文件的文件比較小，使得它非常適合使用於嵌入式系統。
作者將BusyBox稱爲“嵌入式Linux的瑞士軍刀”。
在以前，Docker 官方爲了壓縮容量，保證容器的啓用，其實都在使用 busybox，但後期，Docker 官方開始使用 Alpine 來替代 busybox。
獲取官方鏡像
可以使用 docker pull 指令下載 busybox:latest 鏡像：
PS C:\Users\yhu> docker pull busybox:latest
latest: Pulling from library/busybox
ec562eabd705: Pull complete
Digest: sha256:5eef5ed34e1e1ff0a4ae850395cbf665c4de6b4b83a32a0bc7bcb998e24e7bbb
Status: Downloaded newer image for busybox:latest
docker.io/library/busybox:latest
What's Next?
View a summary of image vulnerabilities and recommendations → docker scout quickview busybox:latest
PS C:\Users\yhu>
下載後，可以看到 busybox 鏡像只有 4.26 MB：
PS C:\Users\yhu> docker image ls
REPOSITORY TAG IMAGE ID CREATED SIZE
repo-docker.isharkfly.com/docker-hub/visatrack latest a329341dbaeb 3 days ago 522MB
repo-docker.isharkfly.com/docker-hub/visatrack <none> f5f9d8b3b410 3 days ago 522MB
alpine/git latest 80ed206c002b 7 days ago 50.4MB
data-mq-service 0.0.1-SNAPSHOT 7eb277a365d6 3 weeks ago 475MB
docsify-docs 0.0.1 32062033284a 6 weeks ago 1.13GB
<none> <none> 0ebfbefe1d52 6 weeks ago 1.13GB
alpine latest 05455a08881e 3 months ago 7.38MB
zchub-crawler latest b20aa408fe8f 7 months ago 1.6GB
mq-service 0.0.1-SNAPSHOT 308dd50eb67a 7 months ago 441MB
reso-web-api-reference-server-odata-manager-app latest 27cdaae03879 8 months ago 441MB
reso-builder latest cabba9a35a22 8 months ago 1.47GB
busybox latest 65ad0d468eb1 11 months ago 4.26MB
tutor-service 0.0.1-SNAPSHOT 20d2f52a1fc4 13 months ago 521MB
sharkfly-wechat-service 0.0.1-SNAPSHOT 0d3e7843994e 13 months ago 465MB
eclipse-temurin 17-jdk-alpine 9a0a4e74d117 13 months ago 358MB
rabbitmq 3.11-management 04a3a28a368b 13 months ago 255MB
framework-spring-docker 0.0.1-SNAPSHOT 42e51829e8c7 15 months ago 379MB
adoptopenjdk/openjdk11-openj9 alpine b533cd6150ba 15 months ago 379MB
mysql/mysql-server latest 1d9c2219ff69 16 months ago 496MB
docker101tutorial latest e60bd4e10534 17 months ago 47MB
alpine/git <none> 22d84a66cda4 17 months ago 43.6MB
PS C:\Users\yhu>
如果只說是大小來說，Alpine 也大不了多少，但 Alpine 提供了更多的功能。
這也就是爲什麼 Docker 官方切換到 Alpine 的原因。
運行 busybox
啓動一個 busybox 容器，並在容器中執行 grep 命令。
從啓動的速度來看，那就是幾乎是光速了。
PS C:\Users\yhu> docker run -it busybox
/ # grep
BusyBox v1.36.1 (2023-05-18 22:34:17 UTC) multi-call binary.
Usage: grep [-HhnlLoqvsrRiwFE] [-m N] [-A|B|C N] { PATTERN | -e PATTERN... | -f FILE... } [FILE]...
Search for PATTERN in FILEs (or stdin)
-H Add 'filename:' prefix
-h Do not add 'filename:' prefix
-n Add 'line_no:' prefix
-l Show only names of files that match
-L Show only names of files that don't match
-c Show only count of matching lines
-o Show only the matching part of line
-q Quiet. Return 0 if PATTERN is found, 1 otherwise
-v Select non-matching lines
-s Suppress open and read errors
-r Recurse
-R Recurse and dereference symlinks
-i Ignore case
-w Match whole words only
-x Match whole lines only
-F PATTERN is a literal (not regexp)
-E PATTERN is an extended regexp
-m N Match up to N times per file
-A N Print N lines of trailing context
-B N Print N lines of leading context
-C N Same as '-A N -B N'
-e PTRN Pattern to match
-f FILE Read pattern from file
/ #
查看容器內的掛載信息。
/ # mount
overlay on / type overlay (rw,relatime,lowerdir=/var/lib/docker/overlay2/l/K7LGRMOMB4YBJOAIY37TDH27OH:/var/lib/docker/overlay2/l/WV2IR37DT2RO7IBXLLNKC5WMBI,upperdir=/var/lib/docker/overlay2/deeb782171b9c2a33054df6b46a3125dc7d283d3af2136a4cc2aa84ec9c9a388/diff,workdir=/var/lib/docker/overlay2/deeb782171b9c2a33054df6b46a3125dc7d283d3af2136a4cc2aa84ec9c9a388/work)
proc on /proc type proc (rw,nosuid,nodev,noexec,relatime)
tmpfs on /dev type tmpfs (rw,nosuid,size=65536k,mode=755)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=666)
sysfs on /sys type sysfs (ro,nosuid,nodev,noexec,relatime)
tmpfs on /sys/fs/cgroup type tmpfs (rw,nosuid,nodev,noexec,relatime,mode=755)
cpuset on /sys/fs/cgroup/cpuset type cgroup (ro,nosuid,nodev,noexec,relatime,cpuset)
cpu on /sys/fs/cgroup/cpu type cgroup (ro,nosuid,nodev,noexec,relatime,cpu)
cpuacct on /sys/fs/cgroup/cpuacct type cgroup (ro,nosuid,nodev,noexec,relatime,cpuacct)
blkio on /sys/fs/cgroup/blkio type cgroup (ro,nosuid,nodev,noexec,relatime,blkio)
memory on /sys/fs/cgroup/memory type cgroup (ro,nosuid,nodev,noexec,relatime,memory)
devices on /sys/fs/cgroup/devices type cgroup (ro,nosuid,nodev,noexec,relatime,devices)
freezer on /sys/fs/cgroup/freezer type cgroup (ro,nosuid,nodev,noexec,relatime,freezer)
net_cls on /sys/fs/cgroup/net_cls type cgroup (ro,nosuid,nodev,noexec,relatime,net_cls)
perf_event on /sys/fs/cgroup/perf_event type cgroup (ro,nosuid,nodev,noexec,relatime,perf_event)
net_prio on /sys/fs/cgroup/net_prio type cgroup (ro,nosuid,nodev,noexec,relatime,net_prio)
hugetlb on /sys/fs/cgroup/hugetlb type cgroup (ro,nosuid,nodev,noexec,relatime,hugetlb)
pids on /sys/fs/cgroup/pids type cgroup (ro,nosuid,nodev,noexec,relatime,pids)
rdma on /sys/fs/cgroup/rdma type cgroup (ro,nosuid,nodev,noexec,relatime,rdma)
misc on /sys/fs/cgroup/misc type cgroup (ro,nosuid,nodev,noexec,relatime,misc)
cgroup on /sys/fs/cgroup/systemd type cgroup (ro,nosuid,nodev,noexec,relatime,name=systemd)
mqueue on /dev/mqueue type mqueue (rw,nosuid,nodev,noexec,relatime)
shm on /dev/shm type tmpfs (rw,nosuid,nodev,noexec,relatime,size=65536k)
/dev/sdd on /etc/resolv.conf type ext4 (rw,relatime,discard,errors=remount-ro,data=ordered)
/dev/sdd on /etc/hostname type ext4 (rw,relatime,discard,errors=remount-ro,data=ordered)
/dev/sdd on /etc/hosts type ext4 (rw,relatime,discard,errors=remount-ro,data=ordered)
devpts on /dev/console type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=666)
proc on /proc/bus type proc (ro,nosuid,nodev,noexec,relatime)
proc on /proc/fs type proc (ro,nosuid,nodev,noexec,relatime)
proc on /proc/irq type proc (ro,nosuid,nodev,noexec,relatime)
proc on /proc/sys type proc (ro,nosuid,nodev,noexec,relatime)
tmpfs on /proc/acpi type tmpfs (ro,relatime)
tmpfs on /proc/kcore type tmpfs (rw,nosuid,size=65536k,mode=755)
tmpfs on /proc/keys type tmpfs (rw,nosuid,size=65536k,mode=755)
tmpfs on /proc/timer_list type tmpfs (rw,nosuid,size=65536k,mode=755)
tmpfs on /sys/firmware type tmpfs (ro,relatime)
/ #
busybox 鏡像雖然小巧，但包括了大量常見的 Linux 命令，讀者可以用它快速熟悉 Linux 命令。
隨着官方對 Docker 容器切換的情況來看，Busybox 對大部分使用 Docker 的人來說可能用不上。
基本上了解下即可。