通过 docker exec sh -c "..." 传递复杂的 shell 脚本

Question

我有一个脚本可以在 linux 主机上的 sh 以及 alpine 容器内正常工作。但是，当我尝试使用 docker exec <containerID> sh -c "<script>" 执行该操作时，它行为不端。脚本的作用是输出类似ps的东西。

systick=$(getconf CLK_TCK); for c in /proc/*/cmdline; do d=$(dirname $c); name=$(grep Name: $d/status); pid=$(basename $d); uid=$(grep Uid: $d/status); uid=$(echo ${uid#Uid:} | xargs); uid=${uid%% *}; user=$(grep :$uid:[0-9] /etc/passwd); user=${user%%:*}; cmdline=$(cat $c|xargs -0 echo); starttime=$(($(awk '{print $22}' $d/stat) / systick)); uptime=$(awk '{print int($1)}' /proc/uptime); elapsed=$(($uptime-$starttime)); echo $pid $user $elapsed $cmdline; done

编辑：sh -c "<script>" 具有相同的行为。

Answer 1

您无法从 docker exec 运行此脚本，因为变量将在发送到容器之前进行插值（即，您将从本地计算机获取值，而不是从容器内获取值）。

为了按您的意愿运行它，您需要在脚本中每次出现$ 时将$ 替换为\$。

更好的方法是将脚本放入文件中，然后使用-v（即-v script.sh:/path/to/script.sh）将文件映射到容器内的某个位置，并通过docker exec /path/to/script.sh调用脚本

Answer 2

第 1 部分：可行的答案

一个工作单线（引用供 Docker 使用）

getProcessDataDef='shellQuoteWordsDef='"'"'shellQuoteWords() { sq="'"'"'"'"'"'"'"'"'"; dq='"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'"'; for arg; do printf "'"'"'"'"'"'"'"'"'%s'"'"'"'"'"'"'"'"' " "$(printf '"'"'"'"'"'"'"'"'%s\n'"'"'"'"'"'"'"'"' "$arg" | sed -e "s@${sq}@${sq}${dq}${sq}${dq}${sq}@g")"; done; printf '"'"'"'"'"'"'"'"'\n'"'"'"'"'"'"'"'"'; }'"'"'; shellQuoteNullSeparatedStream() { xargs -0 sh -c "${shellQuoteWordsDef};"'"'"' shellQuoteWords "$@"'"'"' _; }; getProcessData() { systick=$(getconf CLK_TCK); for c in /proc/*/cmdline; do d=${c%/*}; pid=${d##*/}; name=$(awk '"'"'/^Name:/ { print $2 }'"'"' <"$d"/status); uid=$(awk '"'"'/^Uid:/ { print $2 }'"'"' <"$d"/status); pwent=$(getent passwd "$uid"); user=${pwent%%:*}; cmdline=$(shellQuoteNullSeparatedStream <"$c"); starttime=$(awk -v systick="$systick" '"'"'{print int($22 / systick)}'"'"' "$d"/stat); uptime=$(awk '"'"'{print int($1)}'"'"' /proc/uptime); elapsed=$((uptime-starttime)); echo "$pid $user $elapsed $cmdline"; done; }; getProcessData'
sh -c "$getProcessDataDef"  # or docker exec <container> sh -c "$getProcessDataDef"

工作单行（在引用/转义之前）

shellQuoteWordsDef='shellQuoteWords() { sq="'"'"'"; dq='"'"'"'"'"'; for arg; do printf "'"'"'%s'"'"' " "$(printf '"'"'%s\n'"'"' "$arg" | sed -e "s@${sq}@${sq}${dq}${sq}${dq}${sq}@g")"; done; printf '"'"'\n'"'"'; }'; shellQuoteNullSeparatedStream() { xargs -0 sh -c "${shellQuoteWordsDef};"' shellQuoteWords "$@"' _; }; getProcessData() { systick=$(getconf CLK_TCK); for c in /proc/*/cmdline; do d=${c%/*}; pid=${d##*/}; name=$(awk '/^Name:/ { print $2 }' <"$d"/status); uid=$(awk '/^Uid:/ { print $2 }' <"$d"/status); pwent=$(getent passwd "$uid"); user=${pwent%%:*}; cmdline=$(shellQuoteNullSeparatedStream <"$c"); starttime=$(awk -v systick="$systick" '{print int($22 / systick)}' "$d"/stat); uptime=$(awk '{print int($1)}' /proc/uptime); elapsed=$((uptime-starttime)); echo "$pid $user $elapsed $cmdline"; done; }; getProcessData "$@"

单线衬里发生了什么

shellQuoteWordsDef='shellQuoteWords() { sq="'"'"'"; dq='"'"'"'"'"'; for arg; do printf "'"'"'%s'"'"' " "$(printf '"'"'%s\n'"'"' "$arg" | sed -e "s@${sq}@${sq}${dq}${sq}${dq}${sq}@g")"; done; printf '"'"'\n'"'"'; }'

shellQuoteNullSeparatedStream() {
  xargs -0 sh -c "${shellQuoteWordsDef};"' shellQuoteWords "$@"' _
}

getProcessData() {
  systick=$(getconf CLK_TCK)
  for c in /proc/*/cmdline; do
    d=${c%/*}; pid=${d##*/}
    name=$(awk '/^Name:/ { print $2 }' <"$d"/status)
    uid=$(awk '/^Uid:/ { print $2 }' <"$d"/status)
    pwent=$(getent passwd "$uid")
    user=${pwent%%:*}
    cmdline=$(shellQuoteNullSeparatedStream <"$c")
    starttime=$(awk -v systick="$systick" '{print int($22 / systick)}' "$d"/stat)
    uptime=$(awk '{print int($1)}' /proc/uptime)
    elapsed=$((uptime-starttime))
    echo "$pid $user $elapsed $cmdline"
  done
}

单行代码使用的 Shell-Quoting Helper 发生了什么

为了便于阅读和编辑，上面字符串化的函数如下所示：

# This is the function we're including in our code passed to xargs in-band above:
shellQuoteWords() {
  sq="'"; dq='"'
  for arg; do
    printf "'%s' " "$(printf '%s\n' "$arg" | sed -e "s@${sq}@${sq}${dq}${sq}${dq}${sq}@g")"
  done
  printf '\n'
}

---

第 2 部分：如何创建答案

Python 有一个出色的 shlex.quote() 函数（或 Python 2 中的 pipes.quote()），可用于生成字符串的 shell 引用版本。在这种情况下，可以按如下方式使用：

Python 3.7.6 (default, Feb 27 2020, 15:15:00)
[Clang 7.1.0 (tags/RELEASE_710/final)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> s = r'''
... shellQuoteWords() {
...   sq="'"; dq='"'
...   for arg; do
...     printf "'%s' " "$(printf '%s\n' "$arg" | sed -e "s@${sq}@${sq}${dq}${sq}${dq}${sq}@g")"
...   done
...   printf '\n'
... }
... '''
>>> import shlex
>>> print(shlex.quote(s))
'
shellQuoteWords() {
  sq="'"'"'"; dq='"'"'"'"'"'
  for arg; do
    printf "'"'"'%s'"'"' " "$(printf '"'"'%s\n'"'"' "$arg" | sed -e "s@${sq}@${sq}${dq}${sq}${dq}${sq}@g")"
  done
  printf '"'"'\n'"'"'
}
'

那个结果是 itself 在 shell 中一个完全有效的字符串。也就是说，可以跑：

s='
shellQuoteWords() {
  sq="'"'"'"; dq='"'"'"'"'"'
  for arg; do
    printf "'"'"'%s'"'"' " "$(printf '"'"'%s\n'"'"' "$arg" | sed -e "s@${sq}@${sq}${dq}${sq}${dq}${sq}@g")"
  done
  printf '"'"'\n'"'"'
}
'
eval "$s"
shellQuoteWords "hello world" 'hello world' "hello 'world'" 'hello "world"'

...并获得完全有效的输出。

按照相同的过程生成一个字符串，该字符串评估为getProcessData 的定义。