Sed：从字符串中提取servername

Question

我想使用sed从servername

中提取filenames_for_severname_all

echo "filenames_for_servername_all" | sed -n 's|filenames_for_\(*\)_all|\1|p'

以上都没有回报。谁能解释一下？

Answer 1

您的正则表达式无效，在*修饰符之前缺少一个标记（例如.将匹配任何字符）：

echo "filenames_for_servername_all" | sed -n 's|filenames_for_\(.*\)_all|\1|p'

您也可以尝试grep：

echo "filenames_for_servername_all" | grep -o 'filenames_for_\(.*\)_all'

Answer 2

Pure BASH方式：

s="filenames_for_servername_all"
[[ "$s" =~ _for_([^_]+) ]] && echo "${BASH_REMATCH[1]}"
servername

或者awk：

awk -F_ '{print $3}' <<< "$s"
servername

OR cut：

cut -d_ -f3 <<< "$s"
servername