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Selecting specific variable in log file

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# 1  
Old 07-13-2017
Last entry in log file
Hi there

I am trying to look for a specific word in the log file and I am aware this can be done by grep for example.

As there will be multiple entries for this I want to grep the last one to enter the log... how would I go about this - would I have to use tail?

Thanks in advance

Alex
Last edited by simpsa27; 07-17-2017 at 05:49 AM..
# 2  
Old 09-03-2017
Did you try:
Code:
grep pattern filename | tail -1

# 3  
Old 09-03-2017
How about
Code:
tac file | grep -m1 pattern

? It will save reading / searching through the entire file, esp. interesting for large files.
# 4  
Old 09-03-2017
tac does read the entire file.?
With sed
Code:
sed -n '/pattern/x;$x;$p' file

# 5  
Old 09-04-2017
Quote:
Originally Posted by MadeInGermany
tac does read the entire file.?
.
.
.


No, it doesn't. When grep stops reading the pipe because it found the pattern and exited, tac fills it until it's full and then is killed with SIGPIPE:
Code:
lseek(3, 311877632, SEEK_SET)           = 311877632
read(3, "rag\nTestbeitrag\nTestbeitrag\nTest"..., 8192) = 8192
write(1, "itrag\nTestbeitrag\nTestbeitrag\nTe"..., 4096) = -1 EPIPE (Broken pipe)
--- SIGPIPE {si_signo=SIGPIPE, si_code=SI_USER, si_pid=4061, si_uid=1000} ---
+++ killed by SIGPIPE +++

As you can see, 311869440 (311877632 - 8192) bytes from the file have NOT been read.
This User Gave Thanks to RudiC For This Post:
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