[SOLVED] Impossible demand to use CAT with(?)

hydrurga · 01-27-2018, 06:12 AM

Quote:

Originally Posted by Pomerano

Actually, this was an old task given from one of the former teachers who used to work here. He was mostly known as 'Prf. Magic' because of his perception of achieving the unachievable. This could include unconventional methods of doing the simplest tasks using the most tedious and outdated methods: Such as this one.
He is now retired and lives somewhere in Spain with his hot and young wife, Nastasia. Most likely sipping piña coladas from her belly button on a daily basis

Thank you for the interest

Interesting. Even with Nastasia, he appears to have proved that achieving the unachievable is possible.

Do you have the exact wording of the task that he set?

Pomerano · 01-27-2018, 06:33 AM

Quote:

Originally Posted by pan64

still not sure what do you need. (for example you need the latest log files or the last lines of logfiles or what?).
By the way logrotate will drop out the old messages, so you will see only the latest in /var/log. Regardless of the command you use (awk/grep/perl/cat/whatever)

That is a very interesting suggestion. Would this still include cat somewhere on the line? - That is, without taking away its function of course. If so, would you please consider to put it in a formatted shell-command? Waiting to run an output?

Quote:

Originally Posted by pan64

still not sure what do you need. (for example you need the latest log files or the last lines of logfiles or what?).

My sincerest apologies. I only wish to reduce the output like so:

Quote:

Originally Posted by Pomerano

Now, basically - in plain English - what I ultimately would like to do is...:
To reduce the number of the results who are triggered by the line command cat /var/log/messages. The only condition I have is that it cannot replace the command cat in any way.

In-kind regards - Pom

Pomerano · 01-27-2018, 06:36 AM

Quote:

Originally Posted by hydrurga

Interesting. Even with Nastasia, he appears to have proved that achieving the unachievable is possible.

Do you have the exact wording of the task that he set?

Unfortunately this was one for the books. All you hear are the tales

allend · 01-27-2018, 08:32 AM

By definition, cat dumps the entire contents of a file, so to limit output requires a second tool.
A UUOC, but

Code:

cat /var/log/messages | less +G

keefaz · 01-27-2018, 10:11 AM

Display last few lines in a X terminal

Code:

cat - /var/log/messages <<< $'\e[0;10r\e[0J'

pan64 · 01-27-2018, 10:57 AM

My God, I still don't understand. cat is just a simple reader, it will just read something (file, stdin) and push it toward to the next stage (pipe, file, whatever). The "thing" you need is - I think - something else.

AwesomeMachine · 01-27-2018, 09:00 PM

I still can't figure out what the object is. Do you want to show the most recent log entries in /var/log/messages? Then

Code:

$ cat /var/log/messages

will do that. It will scroll through the whole file, but whats displayed at the end will be the latest messages.

Pomerano · 01-28-2018, 09:14 AM

Quote:

Originally Posted by AwesomeMachine

I still can't figure out what the object is. Do you want to show the most recent log entries in /var/log/messages? Then

Code:

$ cat /var/log/messages

will do that. It will scroll through the whole file, but whats displayed at the end will be the latest messages.

Thank you for the reply. Could this line of code have something added (without removing "cat") to ONLY show the very last results in that very output?
Because that is all I want.

Thanks again!

scasey · 01-28-2018, 09:24 AM

Quote:

Originally Posted by Pomerano

Thank you for the reply. Could this line of code have something added (without removing "cat") to ONLY show the very last results in that very output?
Because that is all I want.

Thanks again!

OH!

Code:

 cat /var/log/messages | tail -2

(-2, because you said results) The number can be anything, and if left off, defaults to 10.
Note that you can just

Code:

tail -2 /var/log/messages

to yield the same result.

jefro · 01-29-2018, 03:37 PM

Use more instead of cat maybe? Maybe less??

pan64 · 01-30-2018, 01:04 AM

or most.
if you wish to use cat, you can do:
cat file | less +G
cat file | most
cat file | tail
but in call cases cat is just superfluous

Pomerano · 02-03-2018, 01:21 PM

Quote:

Originally Posted by scasey

OH!

Code:

 cat /var/log/messages | tail -2

(-2, because you said results) The number can be anything, and if left off, defaults to 10.
Note that you can just

Code:

tail -2 /var/log/messages

to yield the same result.

This was a fantastic reply, however the real deal breaker was this part, simple as that! Thank you so much!

Quote:

Originally Posted by scasey

OH!

Code:

 cat /var/log/messages | tail -2

From a historic point-of-view... this task was not solved by using a UUOC, like $ tail, or such. However, this was all I wanted to know. I will summarize my research for anyone else looking for anything similar at the very bottom...Case closed, thank you! (+1)

Pomerano · 02-03-2018, 01:26 PM

Quote:

Originally Posted by jefro

Use more instead of cat maybe? Maybe less??

Another fantastic reply! "More" did the trick! Thank you so much, Jefro! (+1)

Pomerano · 02-03-2018, 02:00 PM

Quote:

Originally Posted by keefaz

Display last few lines in a X terminal

Code:

cat - /var/log/messages <<< $'\e[0;10r\e[0J'

This also worked, thank you! Although I just can't tell how, at the moment... (+1)

Pomerano · 02-03-2018, 02:03 PM

Quote:

Originally Posted by allend

By definition, cat dumps the entire contents of a file, so to limit output requires a second tool.
A UUOC, but

Code:

cat /var/log/messages | less +G

"UUOC", thank you! Also, the code less did some of it, I just couldn't quite contain it to the extent of keeping it "less" (non-intentional pun) enough to serve its purpose. Although I replaced less +G with just less or less -1. Still very helpful, though, and I am certain that I am the blind one here. Therefore missing the solution. (+ 1)