意外标记“(”附近出现语法错误

Question

rhel_major=$(grep -Eoh [0-9]+\.[0-9]+ /etc/{issue,*release} | head -1 | awk -F'.' '{ print $$1 }')
rhel_minor=$(grep -Eoh [0-9]+\.[0-9]+ /etc/{issue,*release} | head -1 | awk -F'.' '{ print $$2 }')
rhel_release_code=$(echo $$(($(rhel_major) << 8 | $(rhel_minor))))

对于 rhel_release_code 我收到语法错误

rhel_release_code=$(echo $$(("$(rhel_major)" << 8 | $(rhel_minor))))

-bash: command substitution: line 1: syntax error near unexpected token `('
-bash: command substitution: line 1: `echo $$(("$(rhel_major)" << 8 | $(rhel_minor)))'

知道为什么它会抛出这个错误吗？

Answer 1

bash抛出错误，因为它不是有效的 shell 代码。 （这也不是有效的awk代码。）

尝试这个

rhel_major=$(grep -Eoh '[0-9]+\.[0-9]+' /etc/{issue,*release} | awk -F'.' '{ print $1; exit }')
rhel_minor=$(grep -Eoh '[0-9]+\.[0-9]+' /etc/{issue,*release} | awk -F'.' '{ print $2; exit }')
rhel_release_code=$((rhel_major << 8 | rhel_minor))

如果您实际上不需要$rhel_major和$rhel_minor值，您可以$rhel_release使用 直接一步计算awk。