deleted 16 characters in body
Source Link

If you're wanting to do it on log files.

tail -f example.log | sed \
-e "s/FATAL/"$'\e[31m'"&"$'\e[m'"/" \
-e "s/ERROR/"$'\e[31m'"&"$'\e[m'"/" \
-e "s/WARNING/"$'\e[33m'"&"$'\e[m'"/" \
-e "s/INFO/"$'\e[32m'"&"$'\e[m'"/" \
-e "s/DEBUG/"$'\e[34m'"&"$'\e[m'"/"

An example of it working and screenshot below:

echo " [timestamp] production.FATAL Some Message\n" \
"[timestamp] production.ERROR Some Message\n" \
"[timestamp] production.WARNING Some Message\n" \
"[timestamp] production.INFO Some Message\n" \
"[timestamp] production.DEBUG Some Message\n"  | sed \
-e "/\[\]/G" \
-e "s/FATAL/"$'\e[31m'"&"$'\e[m'"/" \
-e "s/ERROR/"$'\e[31m'"&"$'\e[m'"/" \
-e "s/WARNING/"$'\e[33m'"&"$'\e[m'"/" \
-e "s/INFO/"$'\e[32m'"&"$'\e[m'"/" \
-e "s/DEBUG/"$'\e[34m'"&"$'\e[m'"/"

Prints out like this on Mac:

Mac sed logs to add colour

If you're wanting to do it on log files.

tail -f example.log | sed \
-e "s/FATAL/"$'\e[31m'"&"$'\e[m'"/" \
-e "s/ERROR/"$'\e[31m'"&"$'\e[m'"/" \
-e "s/WARNING/"$'\e[33m'"&"$'\e[m'"/" \
-e "s/INFO/"$'\e[32m'"&"$'\e[m'"/" \
-e "s/DEBUG/"$'\e[34m'"&"$'\e[m'"/"

An example of it working and screenshot below:

echo " [timestamp] production.FATAL Some Message\n" \
"[timestamp] production.ERROR Some Message\n" \
"[timestamp] production.WARNING Some Message\n" \
"[timestamp] production.INFO Some Message\n" \
"[timestamp] production.DEBUG Some Message\n"  | sed \
-e "/\[\]/G" \
-e "s/FATAL/"$'\e[31m'"&"$'\e[m'"/" \
-e "s/ERROR/"$'\e[31m'"&"$'\e[m'"/" \
-e "s/WARNING/"$'\e[33m'"&"$'\e[m'"/" \
-e "s/INFO/"$'\e[32m'"&"$'\e[m'"/" \
-e "s/DEBUG/"$'\e[34m'"&"$'\e[m'"/"

Prints out like this on Mac:

Mac sed logs to add colour

If you're wanting to do it on log files.

tail -f example.log | sed \
-e "s/FATAL/"$'\e[31m'"&"$'\e[m'"/" \
-e "s/ERROR/"$'\e[31m'"&"$'\e[m'"/" \
-e "s/WARNING/"$'\e[33m'"&"$'\e[m'"/" \
-e "s/INFO/"$'\e[32m'"&"$'\e[m'"/" \
-e "s/DEBUG/"$'\e[34m'"&"$'\e[m'"/"

An example of it working and screenshot below:

echo " [timestamp] production.FATAL Some Message\n" \
"[timestamp] production.ERROR Some Message\n" \
"[timestamp] production.WARNING Some Message\n" \
"[timestamp] production.INFO Some Message\n" \
"[timestamp] production.DEBUG Some Message\n"  | sed \
-e "s/FATAL/"$'\e[31m'"&"$'\e[m'"/" \
-e "s/ERROR/"$'\e[31m'"&"$'\e[m'"/" \
-e "s/WARNING/"$'\e[33m'"&"$'\e[m'"/" \
-e "s/INFO/"$'\e[32m'"&"$'\e[m'"/" \
-e "s/DEBUG/"$'\e[34m'"&"$'\e[m'"/"

Prints out like this on Mac:

Mac sed logs to add colour

Source Link

If you're wanting to do it on log files.

tail -f example.log | sed \
-e "s/FATAL/"$'\e[31m'"&"$'\e[m'"/" \
-e "s/ERROR/"$'\e[31m'"&"$'\e[m'"/" \
-e "s/WARNING/"$'\e[33m'"&"$'\e[m'"/" \
-e "s/INFO/"$'\e[32m'"&"$'\e[m'"/" \
-e "s/DEBUG/"$'\e[34m'"&"$'\e[m'"/"

An example of it working and screenshot below:

echo " [timestamp] production.FATAL Some Message\n" \
"[timestamp] production.ERROR Some Message\n" \
"[timestamp] production.WARNING Some Message\n" \
"[timestamp] production.INFO Some Message\n" \
"[timestamp] production.DEBUG Some Message\n"  | sed \
-e "/\[\]/G" \
-e "s/FATAL/"$'\e[31m'"&"$'\e[m'"/" \
-e "s/ERROR/"$'\e[31m'"&"$'\e[m'"/" \
-e "s/WARNING/"$'\e[33m'"&"$'\e[m'"/" \
-e "s/INFO/"$'\e[32m'"&"$'\e[m'"/" \
-e "s/DEBUG/"$'\e[34m'"&"$'\e[m'"/"

Prints out like this on Mac:

Mac sed logs to add colour