Hi,
With this post I would like to ask a question.
When using the 'Tail" command, the Terminal applications only outputs/monitors the last line of a file.
I would like to read and display all lines of a log file in Terminal. I'm using these commands ...
tail -f zebra.log
tail -f -n 1000 zebra.log
The man page doesn't help...
Doesn anyone have any suggestions ...
Thank you
MacBook Pro with Retina display, macOS Sierra (10.12.5)
If you have a regular Unix file then
tail -n +1 -f zebra.log
should do exactly what you want.
But the assumption is that you have a regular Unix text file. What does the follow command say about your file?
file zebra.log
And if you display zebra.log with the following command are there extra control characters in it?
cat -vte zebra.log
out put from 'cat -vte' should show a $ for the line feed at the end of each line
If you have <CR><LF> formatted file, then you will see ^M$ at the end of each line
If you have <CR> formatted file, then it will be one line lots of ^M symbols between what you think should be each line.
I'm suspecting your file might be a <CR> formatted file. And if I'm guessing correctly, then the 'file zebra.log' command is going to display
zebra.log: ASCII text, with CR line terminators
But until you gather the information and let us know, it is just a guess on my part.
If you have a regular Unix file then
tail -n +1 -f zebra.log
should do exactly what you want.
But the assumption is that you have a regular Unix text file. What does the follow command say about your file?
file zebra.log
And if you display zebra.log with the following command are there extra control characters in it?
cat -vte zebra.log
out put from 'cat -vte' should show a $ for the line feed at the end of each line
If you have <CR><LF> formatted file, then you will see ^M$ at the end of each line
If you have <CR> formatted file, then it will be one line lots of ^M symbols between what you think should be each line.
I'm suspecting your file might be a <CR> formatted file. And if I'm guessing correctly, then the 'file zebra.log' command is going to display
zebra.log: ASCII text, with CR line terminators
But until you gather the information and let us know, it is just a guess on my part.
The -f flag tells tail to (by default) read the last 10 lines of a file, and pause waiting for more input. If your log has one line of content, that is what will be shown before the pause.
If you want to see the entire log file, then use more(1), or less(1) which begin at the beginning of the log file.
Hi Bob, Many thanks for your feedback. It was very helpfull.
I was using AppleScript to write to the log file and used the wrong line seperator command.
This doesn't work:
set myLogLine to myMessage & return
When using ...
set myLogLine to myMessage & linefeed
the tail command works like expected...
So the type of line terminater/seperator you are using is very important.
Many thanks for all your help.
Well I suggest searching the internet for articles on what you're looking for.
Update:
It seems when using a system log file, the tail command works as expected...
tail -f /var/log/system.log
However, when using the tail command on a custom log file located in the home folder, it shows only the last line ...
Hi, Thanks for your reply. My log file contains 100 lines. That is not the issue. Terminal only displays the last entry...
So the type of line terminater/seperator you are using is very important.
Yup! 🙂
Glad you got it worked out.
Try less zebra.log
tail -f issue
