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tail
Tail helps you keep track of the end of files and stuff!
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Do a "live" tail of a file
tail -f file.txt
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Tail a file while grepping for a specific word at the same time
tail -f somelog.log | grep -w "hello"
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Tail a Caddy log file while grepping for just the source IP, timestamp, and requested URL
sudo tail -f /var/log/caddy/somelog.log | grep --line-buffered -oP '^[0-9]{4}/[0-9]{2}/[0-9]{2} [0-9]{2}:[0-9]{2}:[0-9]{2}\.[0-9]{3}|(?<="remote_ip": ")[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+|(?<="uri": ")[^"]+' | awk 'NR%3==1{timestamp=$0; next} NR%3==2{ip=$0; next} $0!="/"{print "Timestamp: " timestamp ", Source IP: " ip ", Requested URI: " $0}'