如何使用其他命令模拟egrp

Question

我必须模拟egrep以及其他命令的一些选项，主要是awk，但我真的不知道如何在脚本中做到这一点。我知道awk可以识别正则表达式，但它能代替egrep吗？

我真的不知道从哪里开始。

Answer 1

使用的示例文件：

[jaypal:~/Temp] cat file
This is FirstLine
SecondLineEEE
AAAblablabla
ForthLineEEE
FifthLine
LastLine

模拟：

1.egrep -n

[jaypal:~/Temp] egrep -n 'LastLine' file
6:LastLine
[jaypal:~/Temp] awk /LastLine/'{print NR":"$0}' file
6:LastLine

2.egrep -v

[jaypal:~/Temp] egrep -v 'LastLine' file
This is FirstLine
SecondLineEEE
AAAblablabla
ForthLineEEE
FifthLine
[jaypal:~/Temp] awk '/LastLine/{next}1' file
This is FirstLine
SecondLineEEE
AAAblablabla
ForthLineEEE
FifthLine

或（Dennis在评论中指出）

[jaypal:~/Temp] awk '!/LastLine/' file
This is FirstLine
SecondLineEEE
AAAblablabla
ForthLineEEE
FifthLine

3.egrep -i（这仅在gnu awk中）

[jaypal:~/Temp] egrep -i 'lastline' file
LastLine
[jaypal:~/Temp] gawk -v IGNORECASE=1 '/lastline/' file
LastLine

4.egrep -w（这仅在gnu awk中）

[jaypal:~/Temp] egrep -w 'is' file
This is FirstLine
[jaypal:~/Temp] gawk '/<is>/' file
This is FirstLine

5.egrep -f

[jaypal:~/Temp] cat file
This is FirstLine
SecondLineEEE
AAAblablabla
ForthLineEEE
FifthLine
LastLine
[jaypal:~/Temp] cat patternfile
LastLine
is
[jaypal:~/Temp] egrep -f patternfile file
This is FirstLine
LastLine
[jaypal:~/Temp] awk 'NR==FNR{a[$0]++;next} {for (x in a) if ($0~x) print $0}' patternfile file
This is FirstLine
LastLine