CODEWITHSUNDEEP
bashunixtail
maskedjellybean
maskedjellybean

Reputation: 719

Pipe tail output into column

I'm trying to tail a log file and format the output into columns. This gives me what I want without tail:

cat /var/log/test.log | column -t -s "|"

How can I pipe the output of tail -f var/log/test.log into column?

EDIT: Here's an excerpt from the file. I'm manually adding the first line of the file so it could be used as the column headers, but I could format it differently if necessary.

timestamp|type|uri|referer|user_id|link|message
Feb  5 23:58:29 181d5d6339bd drupal_overlake: 1612569509|geocoder|https://overlake.lando/admin/config/development/configuration/config-split/add|https://overlake.lando/admin/config/development/configuration/config-split/add|0||Could not execute query "https://maps.googleapis.com/maps/api/geocode/json?address=L-054%2C%20US&language=&region=US".
Feb  5 23:58:29 181d5d6339bd drupal_overlake: 1612569509|geocoder|https://overlake.lando/admin/config/development/configuration/config-split/add|https://overlake.lando/admin/config/development/configuration/config-split/add|0||Unable to geocode 'L-054, US'.

Upvotes: 3

Views: 1728

Answers (2)

4wk_
4wk_

Reputation: 2733

Actually, there is a way!

Yes, column need all final input to process text... but we can trick it: tail -f is just "regular tail run continuously, right? ツ

watch -n 1 "tail -n 20 myfile.log | column -t"

If you need to keep the first line (as header for instance), you can also do it cleverly:

watch -n 1 "(head -n1 && tail -n20) < users.csv | column -s, -t"

Source: https://avilpage.com/2023/01/pipe-tail-output-into-column.html (from SO' user Chillar Anand)

Upvotes: 0

Barmar
Barmar

Reputation: 781096

You can't do it with the -f option to tail. column can't produce any output until it receives all its input, since it needs to calculate the number of rows and columns by examining all the input. tail -f never stops writing, so column doesn't know when it's done.

You can use

tail -n 100 test.log | column -t -s "|"

to format the last 100 lines of the log.

Upvotes: 2

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