1. tail command: start looking from the end of the text file for the end of a few lines of text files
tail -n filename to specify how many rows to be displayed
tail -f filename real-time display file contents default to the last 10 lines, representing an increase of parameter -n 10
50 -f -n tail filename real-time display 50 lines of the file contents
2. Search the log near the keyword
most commonly used:
cat -n filename | grep "keyword"
Other cases:
cat filename | grep -C 5 'keywords' (display logs that match the string line and around 5 lines)
cat filename | grep -B 5 'keywords' (matching string and display the first 5 rows)
cat filename | grep -A 5 'keys' (5 lines, and the string matching)