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

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0
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1answer
16 views

Possible to prevent multitail from closing “finished” command windows?

Assume a multitail call like the following: multitail -s 2 -l "long-running-command" -l "short-running-command" Now, I would like to have both windows remain open, even after they are finished. ...
3
votes
2answers
68 views

Trace a binary stream from a device file

I'm debugging a binary stream that is coming from a device file. I would like to have the output printed out in real time as hex values. So far I've used tail -f /dev/ttyAPP2 | hexdump -C but after ...
0
votes
1answer
28 views

live tail (tail -f) of file being grepped

i can do tail -f -n20 <file> to see the last 20 lines of the file, live. If i want to grep something, tail -f <file> | grep <pattern>, it will still be live, but will only grep ...
2
votes
4answers
584 views

How to change color of a character while tailing and tr

I regularly use this command line but I would like to change the color of the "|" to green in the output. Does anyone know how I can accomplish this? tail -f file.log | tr '\001' '|' | grep TEST
0
votes
4answers
60 views

How to use tail for multiple files [closed]

I have multiple files. I need to use tail to remove some lines. How can I get the files after using the tail command? I am having problems redirecting the files.
5
votes
2answers
180 views

Command to remove the first N number of lines in input

Background I am running an SSH server and have this user that I want to delete. I cannot delete this user because he is currently running a few processes that I need to kill first. This is the ...
2
votes
2answers
56 views

“cut” hangs when using “tail -f” in combination with “tr”

I'm try to pipe chat log files to some speech output, and want to remove timestamps with cut and remove special characters with tr. Unfortunately, cut seems to halt when using it with tail -f in ...
139
votes
17answers
72k views

How to have tail -f show colored output

I'd like to be able to tail the output of a server log file that has messages like: INFO SEVERE etc, and if it's SEVERE, show the line in red; if it's INFO, in green. What kind of alias can I ...
0
votes
1answer
25 views

Head and Tail of a directory, set by the user

I have this script that will show the user the head or tail of the files that are inside a set directory (currently that is set as '~/bin/new/*'). This script works but i would like to allow the user ...
-5
votes
1answer
503 views

Head and tail command

How can i do this exercise in unix? Create the following command: lshead.bash – list the first few lines of every file in a directory specified by the argument. This command should also allow options ...
1
vote
1answer
20 views

Replicating growing log files in a near real-time manner over the network

I have a server with a bunch of processes writing log files as they run. I need to enable a client host to get a replica of the server-side log files in a near real-time manner. Is there a better way ...
1
vote
5answers
59 views

exit tail when other process is done

I have parallel --j 2 -- "sh script1" "sh script2" where script1 and script2 log in files log1 and log2 I would like to change this to: parallel --j 3 -- "sh script1" "sh script2" "tail -f log1 ...
12
votes
5answers
5k 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". ...
1
vote
1answer
55 views

tail: illegal option — -53\r error while using head and tail on same file in single script

I am using a=`head -1 Rt.in` to get first value from my file and I am saving it as a variable then I am using same variable to tail -$a to tail last lines from my input. But it is giving an ...
4
votes
1answer
66 views

Is this tail behavior in Grouping Commands specified by POSIX?

Using tail combined with other standard tools in Grouping Commands can make some powerful constructions. For example, to get the first and last line of a file: $ seq 10 > file $ { head -n1; tail ...
0
votes
1answer
48 views

How to tail -f against a file which is rolled every 500MB / daily?

I would like to do the following to monitor for a pattern in a log file: tail -f ./app.log | grep "My Pattern: .*" >> ./MyPattern.txt & This is working fine until the app.log reaches ...
1
vote
2answers
237 views

How can I print the second to last line of many files into one file? [duplicate]

I have many CSV files in one directory which have various lengths. I'd like to put the second to last line of each file into one file. I tried something like tail -2 * | head -1 > file.txt, then ...
5
votes
1answer
2k 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 ...
4
votes
2answers
29 views

Interactive, tabbed live tail of multiple files?

I'm often tailing multiple files, and even with a terminal multiplexer (ie tmux or screen) it's still annoying to have multiple windows/shell sessions dedicated to watching multiple files. Is there ...
18
votes
6answers
16k views

Best way to follow a log and execute a command when some text appears in the log

I have a server log that outputs a specific line of text into its log file when the server is up. I want to execute a command once the server is up, and hence do something like the following: tail -f ...
4
votes
4answers
439 views

Prevent tail from modifying the charset of the terminal

In a Linux terminal (CentOS) I am using the command tail --follow=name my-rolling-file.log in order to see the logs of my application. Sometimes in the log there is some binary data dumped (I dump ...
3
votes
1answer
296 views

POSIX head and tail not feature equivalent

The documentation for POSIX tail's -n option says that The origin for counting shall be 1; that is, -n +1 represents the first line of the file, -n -1 the last. So tail -n 10 (used later on the ...
0
votes
2answers
58 views

Monitor a logfile and execute different commands depending on different conditions

I have a logfile which I want to monitor and depending on which condition is met, different commands should be executed. I found a solution that comes close to this here. Unfortunately it doesn't ...
4
votes
2answers
622 views

How to tail a log file by time?

Say my log file(log.txt) is something like 2014-01-01 22:30:30 something happened.... 2014-01-01 22:30:31 something happened.... 2014-01-01 22:30:41 something happened.... I want to tail this file ...
15
votes
3answers
2k 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 ...
52
votes
6answers
85k views

cat line X to line Y on a huge file

Say I have a huge text file (>2GB) and I just want to cat the lines X to Y (e.g. 57890000 to 57890010). From what I understand I can do this by piping head into tail or viceversa, i.e. head -A ...
1
vote
1answer
56 views

What is the reverse of tail -c +K?

I was reading this thread. The command tail -c +K /tmp/1 outputs bytes starting with the Kth of each file. From man tail -c, --bytes=K output the last K bytes; alternatively, use -c ...
34
votes
8answers
17k views

How to obtain inverse behavior for `tail` and `head`?

Is there a way to head/tail a document and get the reverse output; because you don't know how many lines there are in a document? I.e. I just want to get everything but the first 2 lines of foo.txt ...
24
votes
2answers
7k views

The 'less' command-line equivalent of 'tail -f'

I would like to open up a file using less, and have it automatically scroll the file similar to tail -f. I know that I can do less file, and then hit Shift-F to forward forever; like tail -f. I need ...
5
votes
2answers
4k 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 ...
2
votes
3answers
347 views

View only the new entries in a growing log file

tail -f x.log I use this command to see a growing log file in the command prompt. I am interested only in seeing the log lines that are written to the file after running tail -f and not interested ...
1
vote
1answer
61 views

Can someone explain this tail + line to me?

I'm looking through some of the scripts that are on the servers and came across an 80MB shell script. Naturally curious I decided to look in there and came across this line: tail +4802 $0 | zcat - | ...
6
votes
4answers
3k views

is there an alternative to tail -f that has convenient scrolling? [duplicate]

I'm usually inside GNU Screen or tmux, which doesn't give me excellent scrolling functionality. Is there an alternative to tail -f that allows me to quickly scroll up? A tool that is like most is to ...
24
votes
4answers
6k views

monitor files (ala tail -f) in an entire directory (even new ones)

I normally watch many logs in a directory doing tail -f directory/*. The problem is that a new log is created after that, it will not show in the screen (because * was expanded already). Is there a ...
0
votes
1answer
87 views

Clear terminal window before tail -f output

I have the following script running every 3 minutes with cron: #!/bin/bash cd ~/Documents/Fetch/ wget remotehost/data.txt --output-document=tmp cp tmp data.txt rm tmp To fetch a self-generated php ...
6
votes
3answers
3k 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 ...
3
votes
2answers
137 views

Check if conditional with awk for matches in logfile

I want to check the auth.log file for accepted sshd connections and execute an action if any are found. Here is my code: tail -f /var/log/auth.log | awk '{ if($0 ~ /sshd/ && $0 ~ /Accepted/) ...
20
votes
9answers
37k views

Command to display first few and last few lines of a file

I have a file with many rows, and each row has a timestamp at the starting, like [Thread-3] (21/09/12 06:17:38:672) logged message from code..... So, I frequently check 2 things from this log file. ...
1
vote
1answer
58 views

tail -f error_log | cowsay

I'm watching the error logs on my local setup. I'd like to have the errors print out in cowsay, you know, for fun. tail -f error_log | cowsay doesn't work. Any ideas?
4
votes
5answers
894 views

Only output most recent 10 (or n) lines of a lengthy command output

I have a command that outputs thousands of lines. I actually need these lines in order to see the progress of the command. But I do not need to see more than the 10 most recent lines. How can I do ...
4
votes
3answers
440 views

Redirect the tail output to a file then stop when match found

there is this log file that data coming in is continuous. what i wanted to happen is to tail -f this log file then redirect it to a file with the ff conditions example of the log files content ...
6
votes
1answer
675 views

Does less have a feature like tail --follow=name (-F)

The command less can be used to replace tail in tail -f file to provide features like handling binary output and navigating the scrollback: less +F file The + prefix means "pretend I type that ...
4
votes
4answers
1k views

Show filename at begining of each line when tailing multiple files at once?

when tailing multiple files at once as shown below, is any there any way to show the file name at the start of each line? tail -f one.log two.log current output ==> one.log <== contents of ...
1
vote
1answer
81 views

“tail -f” in GNOME Terminal - scrolling to previous lines breaks if there's been lots of subsequent output

I'm viewing a log file with "tail -f" using GNOME Terminal. The log has a lot of input constantly coming into it, and what I find happens is that I scroll up to a previous section, and I'm reading ...
1
vote
4answers
2k views

Tail -f the most recent log file

In a few spots I got this to work ls -rt /path/to/log/file/ | tail -1 | xargs tail -f But I can't figure out why it won't always work (This is quick fix until I get the log rolling fixed here)
7
votes
1answer
528 views

Is `tail -f` more efficient than `less +F`?

This article pointed out some reasons to use less +F over tail -f. Most of the reasons are about the features, not technical reasons: less +F can highlight, search, navigate through file. How about ...
3
votes
2answers
465 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 ...
2
votes
2answers
114 views

Print file contents and delete the printed content* from the file

In Linux, from a bash shell, how can I print the contents of a file and remove the content I just printed content from the file? I have a program writing texts to a file repeatedly. On a Linux shell ...
3
votes
4answers
878 views

How to tail a file over the network?

How can I tail -f a file that over the network, say at \\192.168.2.130\public\print.log? I have tried the variations of the following: tail -f //192.168.2.130/Southpaw/Tactic/print.log which erred ...
2
votes
1answer
79 views

Is it possible to tail -f output to a single line?

less has an option -S or --chop-lines which prevents lines from wrapping and shows output as one line (often extended beyond screen). Is it possible to do this with tail -f? The tail man page ...