Amazon Interview Question for

妖精的尾巴

grep -rnw '/path/to/somewhere/' -e 'pattern'

-r or -R is recursive,
-n is line number, and
-w stands for match the whole word.

roommate

grep -rnw '/path/to/somewhere/' -e 'pattern'

安吉拉

Do you mean extract all the lines contains "Error" and move into a new file?