You can add some additional parameters to your grep command, to search for keywords or phrases in files, to also show you the files that match before or after your match.
This is especially useful if the lines before or after that match are relevant for your search queries.
A normal grep looks like this.
$ grep 'keyword' /path/to/file.log
To also show you the lines before your matches, you can add -B to your grep.
$ grep -B 4 'keyword' /path/to/file.log
The -B 4 tells grep to also show the 4 lines before the match.
Alternatively, to show the log lines that match after the keyword, use the -A parameter.
$ grep -A 2 'keyword' /path/to/file.log
In this example, it will tell grep to also show the 2 lines after the match.
Because this will increase your output from a grep, you can also add the --color parameter (or to please US/UK folks, the --colour also works) to highlight your actual keywords.
A complete example, that shows the 5 lines before the match and 2 lines after the match, while highlighting the keyword(s), looks like this.
$ grep -B 5 -A 2 --color 'keyword' /path/to/file.log
And that’s it!