问题
Why doesn't something like this work:
echo 4 | awk --assign=abc=4 '/$abc/'
The actual example is much more complicated. Basically I have a regex I need repeated several times so I'm storing it in abc. Is there any way to expand an awk variable in /<regex>/? I've tried single and double quotes, every combination. I really need that line to be single quoted because I have several double quotes, it actually looks more like awk --assign=test=something '/$test/ { a lot of stuff here inc $test several times with double quotes; }'
回答1:
awk doesn't use variables between / and / regex:
Following equivalent will work with same effect using ~ regex operator:
echo 4 | awk --assign=abc=4 '$0 ~ abc'
4
来源：https://stackoverflow.com/questions/19188617/awk-variable-expansion-in-regex