linux - 如何用其他命令模拟egrep？

Question

我必须模拟 egrep 加上其他命令的一些选项，主要是 awk，但我不太了解如何在脚本中执行此操作。我知道 awk 可以识别正则表达式，但它可以替代 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(如丹尼斯在评论中指出的那样)

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

3。 egrep -i(这仅适用于 gnu awk)

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

4。 egrep -w(这只在 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