运行两年的Bash内核版本比较脚本突发整数比较语法错误

问题背景 #

以下是用于Linux内核补丁版本更新时编译安装内核的Bash逻辑：

post_kernel_postinst() {
    # 提取新内核和当前内核版本
    NEW_KV=$(eselect kernel show | tail -n 1 | grep -oE '[0-9\.]{5,7}')
    CURRENT_KV=$(uname -r | grep -oE '[0-9\.]{5,7}')
  
    # 将版本字符串拆分为数组
    IFS='.' read -r -a NEW_KV_ARR <<< "$NEW_KV"
    IFS='.' read -r -a CURRENT_KV_ARR <<< "$CURRENT_KV"

    # 获取补丁版本号
    NEW_KERNEL_PATCH_VERSION="${NEW_KV_ARR[2]}"
    CURRENT_KERNEL_PATCH_VERSION="${CURRENT_KV_ARR[2]}"

    echo "NEW_KV $NEW_KV"
    echo "CURRENT_KV $CURRENT_KV"
    echo "NEW_KERNEL_PATCH_VERSION $NEW_KERNEL_PATCH_VERSION"
    echo "CURRENT_KERNEL_PATCH_VERSION $CURRENT_KERNEL_PATCH_VERSION"

    # 检查新内核版本是否高于当前版本
    if [[ $((NEW_KERNEL_PATCH_VERSION - CURRENT_KERNEL_PATCH_VERSION)) -ge 0 ]]; then
      echo "GoodBye!!"
    fi
}

该脚本正常运行两年多，但近两个月触发如下语法错误：

NEW_KV 6.14.3
CURRENT_KV 6.14.3
NEW_KERNEL_PATCH_VERSION 3
CURRENT_KERNEL_PATCH_VERSION 3
bash: 3: syntax error: invalid arithmetic operator (error token is "")

两年未修改脚本，无法确定系统哪项变更引发问题。

排查过程 #

感谢各位帮助，已为eselect添加--color=no参数移除颜色转义字符，但问题仍存在。修改脚本添加函数调用后，发现不同执行方式结果不一致：

修改后的脚本：

post_kernel_postinst() {
    # 提取新内核和当前内核版本
    NEW_KV=$(eselect --color=no kernel show | tail -n 1 | grep -oE '[0-9\.]{5,7}')
    CURRENT_KV=$(uname -r | grep -oE '[0-9\.]{5,7}')
  
    # 将版本字符串拆分为数组
    IFS='.' read -r -a NEW_KV_ARR <<< "$NEW_KV"
    IFS='.' read -r -a CURRENT_KV_ARR <<< "$CURRENT_KV"

    # 获取补丁版本号
    NEW_KERNEL_PATCH_VERSION="${NEW_KV_ARR[2]}"
    CURRENT_KERNEL_PATCH_VERSION="${CURRENT_KV_ARR[2]}"

    echo "NEW_KV $NEW_KV"
    echo "CURRENT_KV $CURRENT_KV"
    echo "NEW_KERNEL_PATCH_VERSION $NEW_KERNEL_PATCH_VERSION"
    echo "CURRENT_KERNEL_PATCH_VERSION $CURRENT_KERNEL_PATCH_VERSION"

    # 检查新内核版本是否高于当前版本
    if [[ $((NEW_KERNEL_PATCH_VERSION - CURRENT_KERNEL_PATCH_VERSION)) -ge 0 ]]; then
      echo "GoodBye!!"
    fi
}

post_kernel_postinst

执行输出：

greninja@ash ~ $ source ./temp.sh
NEW_KV 6.14.3
CURRENT_KV 6.14.3
NEW_KERNEL_PATCH_VERSION 3
CURRENT_KERNEL_PATCH_VERSION 3
bash: 3: syntax error: invalid arithmetic operator (error token is "")

greninja@ash ~ $ post_kernel_postinst
NEW_KV 6.14.3
CURRENT_KV 6.14.3
NEW_KERNEL_PATCH_VERSION 3
CURRENT_KERNEL_PATCH_VERSION 3
bash: 3: syntax error: invalid arithmetic operator (error token is "")

greninja@ash ~ $ ./temp.sh
NEW_KV 6.14.3
CURRENT_KV 6.14.3
NEW_KERNEL_PATCH_VERSION 3
CURRENT_KERNEL_PATCH_VERSION 3
GoodBye!!

最终解决 #

为grep添加--color=no参数后问题解决，感谢@Charles_Duffy建议使用set -x发现grep默认启用--color=always，以及@benschumacher指出问题源于多余字符。

解决后输出：

greninja@ash ~ $ source ./temp.sh
NEW_KV 6.14.3
CURRENT_KV 6.14.3
NEW_KERNEL_PATCH_VERSION 3
CURRENT_KERNEL_PATCH_VERSION 3
GoodBye!!

greninja@ash ~ $ post_kernel_postinst
NEW_KV 6.14.3
CURRENT_KV 6.14.3
NEW_KERNEL_PATCH_VERSION 3
CURRENT_KERNEL_PATCH_VERSION 3
GoodBye!!

greninja@ash ~ $ ./temp.sh
NEW_KV 6.14.3
CURRENT_KV 6.14.3
NEW_KERNEL_PATCH_VERSION 3
CURRENT_KERNEL_PATCH_VERSION 3
GoodBye!!

内容的提问来源于stack exchange，提问作者GreninjaShuriken4