shell - BASH : Find number in text -> variable

Question

我几乎不需要社区的帮助:

我在一个大文本文件中有这两行:

Connected clients: 42  
4 ACTIVE CLIENTS IN LAST 20 SECONDS  

如何查找、提取数字并将其分配给变量？

clients=42
active=4

SED、AWK、GREP？我应该使用哪一种？

Answer 1

clients=$(grep -Po '^(?<=Connected clients: )([0-9]+)$' filename)
active=$(grep -Po '^([0-9]+)(?= ACTIVE CLIENTS IN LAST [0-9]+ SECONDS$)' filename)

或者

clients=$(sed -n 's/^Connected clients: \([0-9]\+\)$/\1/p' filename)
active=$(sed -n 's/^\([0-9]\+\) ACTIVE CLIENTS IN LAST [0-9]\+ SECONDS$/\1/p' filename)