Sponsored Content
Top Forums UNIX for Advanced & Expert Users How to read a fast written log file at Real time speed? Post 302937623 by cool.aquarian on Friday 6th of March 2015 03:15:47 PM
Old 03-06-2015
Hi there..

I managed to improve the performance by 10-fold for real time reading.

I analysed and found that most time was being taken by
Code:
while IFS= read -r line

I replaced the while loop with awk to read a single logical unit(each about 6000 lines) in one go.

Code:
tail -F --lines=10000000 --retry --max-unchanged-stats=10 "$FILE_NAME" | awk -f awk-script.txt

Now the speed of reading is able to more than keep up with speed of write.
Even when the file gets rolled over, it is able to catch-up with the new file and gives message like:
tail: `<file-name>' has been replaced; following end of new file

Last edited by cool.aquarian; 03-06-2015 at 06:40 PM..
 

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

log users real time

hi.... how i can configurator a log file on real time....on unix solaris.... thanks a lot.... Best Regards... (3 Replies)
Discussion started by: chanfle
3 Replies

2. Shell Programming and Scripting

Real time log file redirect

Hi all, i would like to write the shell script program, it can monitor the access_log "real time" when the access_log writing the line contain "abcdef" the program will be "COPY" this line into a file named "abcdef.txt", do the same thing if the contain "123456" "COPY" it into a file named... (3 Replies)
Discussion started by: eric_wong_ch
3 Replies

3. Shell Programming and Scripting

Perl or Shell script to read a transaction log in real time

Hello, I have a Apache webserver running on RedHat. Its primary function is a proxy server for users accessing the internet. I have a transaction log that logs every transactions of every users. For users trying to access certain sites/content the transactions goes into a 302 redirect loop and... (2 Replies)
Discussion started by: bruno406
2 Replies

4. Programming

Read/Write a fairly large amount of data to a file as fast as possible

Hi, I'm trying to figure out the best solution to the following problem, and I'm not yet that much experienced like you. :-) Basically I have to read a fairly large file, composed of "messages" , in order to display all of them through an user interface (made with QT). The messages that... (3 Replies)
Discussion started by: emitrax
3 Replies

5. Filesystems, Disks and Memory

data from blktrace: read speed V.S. write speed

I analysed disk performance with blktrace and get some data: read: 8,3 4 2141 2.882115217 3342 Q R 195732187 + 32 8,3 4 2142 2.882116411 3342 G R 195732187 + 32 8,3 4 2144 2.882117647 3342 I R 195732187 + 32 8,3 4 2145 ... (1 Reply)
Discussion started by: W.C.C
1 Replies

6. Shell Programming and Scripting

Read/Search file being written to giving error due to timing issues

The following is a piece of code to rename LOG_FILE_NEW to LOG_FILE once you get a result (either RUNNING or SHUTDOWN) RESULT="" sleep 30 while ; do sleep 10 RESULT=`sed -n '/RUNNING/'p ${LOG_FILE_NEW}` if ; then RESULT=`sed -n '/SHUTTING_DOWN/'p ${LOG_FILE_NEW}` fi done mv... (3 Replies)
Discussion started by: sonorous
3 Replies

7. HP-UX

HP-UX real time audit log writing

Hey all, I have a problem I was hoping to get some help on. So I have my two auditfiles, audfile1 and audfile2 that can be written to, I want to have the text version of them write to an NFS mount that I have set up. So i already know that i can do .secure/etc/audsp audfile1 > //nfsmount/folder/... (5 Replies)
Discussion started by: CleverRiver6
5 Replies

8. Shell Programming and Scripting

[solved] How to see log in real time?

Hi people I have a bash script with a line like this: python example.py >> log & But i can't see anything in the log file while python program is running only if the program ends seems to write the log file. "$ cat log" for example don't show anything until the program ends. Is there... (4 Replies)
Discussion started by: Tieso
4 Replies

9. Shell Programming and Scripting

Archiving or removing few data from log file in real time

Hi, I have a log file that gets updated every second. Currently the size has grown to 20+ GB. I need to have a command/script, that will try to get the actual size of the file and will remove 50% of the data that are in the log file. I don't mind removing the data as the size has grown to huge... (8 Replies)
Discussion started by: Souvik Patra
8 Replies

10. Shell Programming and Scripting

Log all the commands input by user at real time in /var/log/messages

Below is my script to log all the command input by any user to /var/log/messages. But I cant achieve the desired output that i want. PLease see below. function log2syslog { declare COMMAND COMMAND=$(fc -ln -0) logger -p local1.notice -t bash -i -- "$USER:$COMMAND" } trap... (12 Replies)
Discussion started by: invinzin21
12 Replies
TAIL(1) 								FSF								   TAIL(1)

NAME
tail - output the last part of files SYNOPSIS
tail [OPTION]... [FILE]... DESCRIPTION
Print the last 10 lines of each FILE to standard output. With more than one FILE, precede each with a header giving the file name. With no FILE, or when FILE is -, read standard input. Mandatory arguments to long options are mandatory for short options too. --retry keep trying to open a file even if it is inaccessible when tail starts or if it becomes inaccessible later -- useful only with -f -c, --bytes=N output the last N bytes -f, --follow[={name|descriptor}] output appended data as the file grows; -f, --follow, and --follow=descriptor are equivalent -F same as --follow=name --retry -n, --lines=N output the last N lines, instead of the last 10 --max-unchanged-stats=N with --follow=name, reopen a FILE which has not changed size after N (default 5) iterations to see if it has been unlinked or renamed (this is the usual case of rotated log files) --pid=PID with -f, terminate after process ID, PID dies -q, --quiet, --silent never output headers giving file names -s, --sleep-interval=S with -f, sleep for approximately S seconds (default 1.0) between iterations. -v, --verbose always output headers giving file names --help display this help and exit --version output version information and exit If the first character of N (the number of bytes or lines) is a `+', print beginning with the Nth item from the start of each file, other- wise, print the last N items in the file. N may have a multiplier suffix: b for 512, k for 1024, m for 1048576 (1 Meg). With --follow (-f), tail defaults to following the file descriptor, which means that even if a tail'ed file is renamed, tail will continue to track its end. This default behavior is not desirable when you really want to track the actual name of the file, not the file descrip- tor (e.g., log rotation). Use --follow=name in that case. That causes tail to track the named file by reopening it periodically to see if it has been removed and recreated by some other program. AUTHOR
Written by Paul Rubin, David MacKenzie, Ian Lance Taylor, and Jim Meyering. REPORTING BUGS
Report bugs to <bug-coreutils@gnu.org>. COPYRIGHT
Copyright (C) 2002 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICU- LAR PURPOSE. SEE ALSO
The full documentation for tail is maintained as a Texinfo manual. If the info and tail programs are properly installed at your site, the command info tail should give you access to the complete manual. tail (coreutils) 4.5.3 February 2003 TAIL(1)
All times are GMT -4. The time now is 02:04 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy