Usually we need to use a condition query when looking up keywords.
Through this article you will learn how to use the linux grep command to perform or/and/not condition queries for keywords.
grep or condition
1. Use regular
➜ grep -n -C 3 "[A|B] num" man-grep.txt
➜ grep -n -C 3 -E "[A|B] num" man-grep.txt
The results are consistent.
2. Use grep -e
With the grep -e option, only one parameter can be passed. Use multiple -e options in a single command to get multiple patterns to implement OR operations.
➜ grep -n -e "A num" -e "B num" -C 3 man-grep.txt
grep and condition
➜ grep -n -C 3 "A num" man-grep.txt | grep "B num"
grep not condition
Use grep -v
➜ grep -n "A num" man-grep.txt | grep -v "B num"