Watching updates at the end of a file, with or without the tail utility

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how can I redirect the grepped output of tail -f to a file? [duplicate]

I want to do this: tail -f /var/log/apache2/access.log | grep 'POST \/review' But I want the output to go to a file and I want this to run constantly for a day or two. I tried a simple script ...
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1answer
23 views

tail-ing a filename that is a date [duplicate]

I am creating a logfile from kermit named the current date (which is in the format of DD MMM YYYY - which can not be changed AFAIK), and using the file name as today's date. I then have a Bash script ...
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5answers
77 views

Using head and tail to grab different sets of lines and saving into same file

So this is for homework, but I will not be asking the specific homework question. I need to use head and tail to grab different sets of line from one file. So like lines 6-11 and lines 19-24 and ...
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1answer
25 views

Use tail and grep to send an IRC message?

How do I use a command like: tail -f /home/user/log.txt | grep '!calladmin\|admin' To send an IRC message to me when !calladmin or admin are posted in the log? Or is there an easier way to do ...
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1answer
34 views

Hash different, is it safe?

The first time I downloaded Tails image which is with different sha256sum than the webpage giving, so I downloaded it once again and this time it is correct. Then I unpakeged all the files inside the ...
0
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1answer
84 views

Pipe stdout to command on stdout

If I had a running process like tail -F watch.txt and I wanted to capture the stdout from this running process and pipe it to another command on stdout how could this be done? Here's an example of a ...
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0answers
68 views

Repeatedly execute bash command while there's no output from another process

I'm running fs_usage to detect access to an object on my filesystem. sudo fs_usage -w | grep -E 'object' I now want to run a touch command on that object every 5 seconds as long as there's no new ...
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2answers
85 views

Coloring tail output with perl

tail -f logfile.log | perl -pe 's/.*foo*/\e[1;41m$&\e[0m/g' will color all the lines containing the pattern "foo" in the logfile.log file. How can I make use of this in order to highlight ...
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2answers
26 views

Getting transient PID from log into a PS search before it dies

I have a transient prelink process populating our audit log, but we're not sure what the process is. The error log gives us the PID, but it disappears pretty much instantly, as the process finishes ...
2
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2answers
445 views

Negative arguments to head / tail

Variants of this question have certainly been asked several times in different places, but I am trying to remove the last M lines from a file without luck. The second most voted answer in this ...
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2answers
557 views

Suppress 'file truncated' messages when using tail

I'm tailing a log file using tail -f messages.log and this is part of the output: Lorem ipsum dolor sit amet, consectetur adipiscing elit. Fusce eget tellus sit amet odio porttitor rhoncus. Donec ...
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Why does GNU head/tail read the whole file? [duplicate]

I have a huge file and want to see its beginning and end. However, when I use head and tail, it apparently tries to read the whole file. Since the file is larger than a terabyte, this takes a very ...
2
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1answer
184 views

splitting a CSV and keeping the header without intermediate files [closed]

I am trying to split a dozen 100MB+ csv files into managable smaller files for a curl post. I have managed to do it but with a lot of temporary files and IO. It's taking an eternity. I am hoping ...
3
votes
1answer
300 views

grep not working in a for loop over a list

I have some log files. And I have a list of user ids. My log files are in a particular format log-yyyy-mm-dd e.g. log-2014-09-30 I am trying to search each userId in the log file. This is what I am ...
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3answers
119 views

Time required to do pipe output to head/tail [duplicate]

There are lots of txt files in a directory. If I do time wc -l *.txt | head it takes real 0m0.032s user 0m0.020s sys 0m0.008s If I do time wc -l *.txt | tail it takes real 0m0.156s ...
6
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1answer
927 views

Tail log file on multiple machines over ssh

I'm trying to tail a log file on multiple remote machines and forward the output to my local workstation. I want connections to close when pressing Ctrl-C. At the moment I have the following function ...
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3answers
352 views

Open a directory and let it update itself using “tail -f”

Similar to my last question: Open a text file and let it update itself; is there a way I could do the same but for a folder instead? As I have a log folder, can I use tail -f with a folder? i.e. $ ...
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2answers
153 views

cygwin, tail -F and rapidly filling/rotatinglogs

I'm using cygwin tail to follow busy java web application logs, on a windows server, generating roughly 16Gb worth of logs a day. I"m constrained to 10MB log sizes, so the files roll very often. ...
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4answers
2k views

Why does “tail -f … | tail” fail to produce any output?

Why does the following command not produce any output? $ tail -f /etc/passwd | tail After reading about buffering, I tried the following to no avail: $ tail -f /etc/passwd | stdbuf -oL tail Note ...
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3answers
905 views

Open a text file and let it update itself

How can I open a text file and let it update itself? Similar to the way top works. I want to open a log file and watch it update itself on the fly. I have just tried: $ tail error.log But just ...
2
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4answers
354 views

Only cat from specific line X (with a pattern) to other specific line Y (with a pattern)

A little extended problem from "cat line x to line y on a huge file": I have a huge file (2-3 GB). I'd like to cat/print only from the line having "foo:" to the line having "goo:". Assume that "foo:" ...
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3answers
87 views

Pulling lines n to m from list of files found

Ultimately I need to grab lines 3-53 from ever csv in each subdirectory. I grabbed the lines like so (cat isn't necessarily required): cat /[path]/[file].csv | head -53 | tail -51 And the files ...
3
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1answer
213 views

“tail -f” show old file after file has been rotated [duplicate]

I have a script running continuously, reading tail -f /var/log/daemon.log The problem is, when the file /var/log/daemon.log gets rotated by logrotate, tail still has "file handle" for the old ...
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2answers
1k views

Coloring different sources for tail

I'm watching different logs by tail -q -f /var/log/syslog -f /var/log/fail2ban.log -f /var/log/nginx/error.log How can I have the output of each log colored differently?
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782 views

How to tail multiple files using tail -0f in Linux/AIX

I tried tailing two files using the option: tail -0f file1.log -0f file2.log In Linux I see an error "tail : can process only one file at a time". In AIX I see the error as "Invalid options". ...
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272 views

scroll through output using `less` or `tail -f` while keeping the header visible [duplicate]

I am trying to scroll through some data formatted thus- NFI T[PSEC] T[K] EKIN(PSI) E(RHO) ECONS ANNEE ANNER !> 1 0.00012 0 0.45873 16.26904 16.72777 ...
6
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1answer
84 views

Not able to see the progression of a file with “tail -f”!

It's a surprise why now this command isn't working which earlier was. See I've the below command to run for backup. ubuntu@ubuntu:~$ sudo tar -cvf /media/ubuntu/My*Linux/ub*data/zebra.tar ...
4
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1answer
83 views

tail -f produces no output in Ubuntu live CD

For some test I start Ubuntu Live from USB. I'm trying to use tail command to show debug log, but it doesn't work. I also test opening two terminals (t1, t2) with this code: t1: touch a t2: ...
3
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1answer
138 views

Grep with spaces suddenly doesn't work

When performing a grep like: $ tail -f apilog_2014.07.09.log | grep "HELLO" | grep "99999" I get the desired output: 12:22:35 server apache2: HELLO FRIEND 99999 12:22:35 server apache2: HELLO ...
2
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1answer
170 views

multitail - custom config (multitail.conf) location

Is it possible to provide a custom location for multitail.conf - or are my only options /etc/multiltail.conf or ~/multitail.conf? I'd like to provide a specific config file that has regexes specific ...
2
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3answers
143 views

What does “tail -f ” do? [duplicate]

I don't understand the function of the option -f added to the tail command. I know that tail views the "last" part of a file. The manual says that -f outputs appended data as the file grows But ...
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2answers
1k views

How do I “cat and follow” a file?

A file is being sequentially downloaded by wget. If I start unpacking it with cat myfile.tar.bz2 | tar -xj, it may unpack correctly or fail with "Unexpected EOF", depending on what is faster. How to ...
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1answer
61 views

How to echo from specific line of a file to another specific line [duplicate]

Assume I have a file with about 10000 lines. How can I print 100 lines, starting from line 1200 to line 1300?
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2answers
2k views

continuous reading from named pipe (cat or tail -f)

I have configured rsyslog to log certain log events to /dev/xconsole: *.*;cron.!=info;mail.!=info |/dev/xconsole /dev/xconsole is a named pipe (fifo). If I want to see what is being logged, I ...
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4answers
2k views

How to get lines 10 to 100 from a 200 line file into a new file [duplicate]

I have file with 200 lines. I need to extract lines from 10 to 100 and put them into a new file. How do you do this in unix/Linux? What are the possible commands you could use?
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2answers
123 views

Temporarily freeze a process upon shell interaction

Let's say on a single console I have tail -F running, showing the output of many log files in realtime. Sometimes I need to run commands there too, however, and examine their output briefly, without ...
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2answers
97 views

tail display whole file and then only changes [duplicate]

My Linux version is 2.6.32-47-server (gcc version 4.4.3 (Ubuntu 4.4.3-4ubuntu5.1) ) #109-Ubuntu SMP Tue May 7 02:17:05 UTC 2013 I am currently doing a tail -f file and life is good. But that only ...
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1answer
82 views

Is it possible to `tail -f /dev/vcs`?

I would like to get a continuous stream of output from the virtual terminal. Is that possible? If not, why is tail -f not working here?
5
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3answers
539 views

tail -f, Determine if a file is no longer being written to [closed]

I am using tail -f to follow the growth of a log file. I am having trouble finding a way to detect if the process that is writing to the log file (when it crashes or is otherwise terminated) is no ...
4
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2answers
648 views

What does tail -f <directory name> do?

I mistakenly executed the following command in the terminal: tail -f /logs/applications/logs* I got the following output: tail: file shrunk! Error 0 I am not sure what exactly happened. I have ...
3
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2answers
354 views

What does tail -0a do?

In the documentation for logstash, they mention the command tail -0a I have never heard of the -a flag and I can't find any information on google, tail --help or the man pages. What is the ...
2
votes
1answer
544 views

Convert newlines to null-delimited when using tail

How can I change the output from tail to use null-terminated lines instead of newlines? My question is similar to this one: How to do `head` and `tail` on null-delimited input in bash?, but differs ...
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1answer
1k views

Do I need to worry about “tail: unrecognized file system type 0xbeefdead”?

I'm trying to follow a regular text file with tail -f -n 50 filename. I get the information from the file just fine, except I always get this error message: tail: unrecognized file system type ...
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3answers
96 views

Is it possible to change the default COUNT value of tail and head?

The less command accepts its defaults with an environment variable LESS, so you can export LESS='-F -g -i -M -R -S -w -X -z-4' at the beginning of your session. Is it possible to change the ...
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2answers
521 views

will tail with piping read whole file?

I want to read a big log file with 10000 lines everytime. and I use this command: tail -c +offset somefile | head -n 10000 my question is, with the piping of head, will tail read the whole file? ...
1
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1answer
797 views

how do i redirect output from tailf & grep to a file [duplicate]

All I wanted is to grep for specific lines in an ongoing log and re-direct it to some file.. tailf log | grep "some words" Now, I want the above command output to get re-directed to some file in ...
0
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1answer
97 views

Need to grep for specific lines from ongoing log and save it in some file

So, let me start with the overall outcome that i want to achieve. There is just one log, which will have info on certain devices, that i am upgrading. I use "tailf log" to monitor the log. Now, ...
10
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4answers
6k views

Grep from the end of a file to the beginning

I have a file with about 30.000.000 lines (Radius Accounting) and I need to find the last match of a given pattern. The command: tac accounting.log | grep $pattern gives what I need, but it's too ...
4
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2answers
58 views

Can less load lines which were appended to a file after opening?

When I am viewing a log file in less is it possible to make less reload the file to get lines which were appended to that file since it was opened?
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1answer
77 views

Stop tailing log

I have a problem, I accidentally did tail -f on a log, but now I cant quit! - Its the anaconda log during a redhat install. Control-C doesn't seem to work, I guess due to it saying sh: no job control ...