Zsh脚本检测OS时出现'= not found'错误，求原因分析

我想用Zsh脚本检测操作系统并加载对应配置，但运行脚本时出现难以理解的load_config:3: = not found错误，错误信息极少无法明确原因。脚本代码及运行日志如下：

原脚本代码 #

function load_config(){
  os=$(uname -a)
  echo $os
  if [[`echo $os | grep -o kali | tail -1` == "kali"]]; then
    for FILE in ~/.config/zsh_config/kali/*.zsh; do
      source $FILE
    done
  elif [[`echo $os | grep -o MANJARO | tail -1` == "MANJARO"]]; then
    for FILE in ~/.config/zsh_config/manjaro/*.zsh; do
      source $FILE
    done
  elif [[`echo $os | grep -o MacBook | tail -1` == "MacBook"]]; then
    for FILE in ~/.config/zsh_config/osx/*.zsh; do
      source $FILE
    done
  else
    echo 'Unknown OS!'
  fi
}

运行日志 #

$ load_config 
Linux kali 5.18.0-kali5-amd64 #1 SMP PREEMPT_DYNAMIC Debian 5.18.5-1kali5 (2022-07-04) x86_64 GNU/Linux
load_config:3: = not found

错误原因 #

这个错误是**[[ 和反引号（）之间缺少空格**导致的。Zsh中[[`是语法关键字，必须和后续表达式保留空格，否则会被解析成一个不存在的命令`[[`（把`[[`和后面的反引号内容连在一起），同时后面的`==`会被错误拆分，最终触发"= not found"的错误。

修复后的脚本 #

function load_config(){
  os=$(uname -a)
  echo $os
  # 给[[后添加空格，同时用$()替代反引号提升可读性
  if [[ $(echo $os | grep -o kali | tail -1) == "kali" ]]; then
    for FILE in ~/.config/zsh_config/kali/*.zsh; do
      source $FILE
    done
  elif [[ $(echo $os | grep -o MANJARO | tail -1) == "MANJARO" ]]; then
    for FILE in ~/.config/zsh_config/manjaro/*.zsh; do
      source $FILE
    done
  elif [[ $(echo $os | grep -o MacBook | tail -1) == "MacBook" ]]; then
    for FILE in ~/.config/zsh_config/osx/*.zsh; do
      source $FILE
    done
  else
    echo 'Unknown OS!'
  fi
}

额外优化建议 #

• 用$()替代反引号：反引号在嵌套使用时容易出现语法问题，$()的可读性和兼容性更优
• 简化系统检测逻辑：可以直接用uname -s获取内核名称，或者lsb_release -i获取发行版信息，避免依赖uname -a中的可变字符串

内容的提问来源于stack exchange，提问作者rivi mizuiro