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

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1answer
4k 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 on-...
0
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1answer
148 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, say,...
19
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4answers
21k 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
105 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?
0
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1answer
147 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 ...
2
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1answer
513 views

Piping periodic data between Python scripts

How to receive data from the environment e.g. bash I am trying to launch two Python scripts in bash and pipe stdout from one of them to stdin of the other. The first script outputs a single number ...
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2answers
1k views

Tail multiple files and output as additional column with 'find' results

Would like to pull the last line of text from a specific (multiple) files in a directory. Additionally, I'd like the results to be in a more traditional column format (like ls) with path, rather than ...
4
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4answers
1k 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 ...
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2answers
255 views

How can I monitor a file that fully recreates during its run?

This is a follow-up question of Why are some file changes not shown in tail -f? With the use of capital F: tail -F I can monitor the output of tail -F ~/.mysql_history from the manual: --...
3
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1answer
142 views

Why are some file changes not shown in tail -f?

I tried to follow the mysql history file with: tail -f ~/.mysql_history in another window I entered as the same user: mysql -u someotheruser -p and none of the following commands are shown in my ...
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2answers
3k views

Show tail of files in a directory?

I have a directory that is too huge to browse by any means. Grepping returns argument lists too long, WINSCP crashes when trying to open the directory. Is there a way I can view just the last 200 ...
91
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4answers
6k views

Does tail read the whole file?

If I want to tail a 25 GB textfile, does the tail command read the whole file? Since a file might be scattered on a disk I imagine it has to, but I do not understand such internals well.
4
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1answer
321 views

How can I colorize head, tail and less, same as I've done with cat?

I've got 'color cat' working nicely, thanks to others (see How can i colorize cat output including unknown filetypes in b&w?). In my .bashrc: cdc() { for fn in "$@"; do source-highlight --...
1
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1answer
94 views

Get last changed content since last read

How can I get the last changed content of a file, since its last read? Something more precise that this: tail - <nr >file_1.txt >file_2.txt where file_2.txt gets the last modified content....
2
votes
1answer
5k views

Search and Filter Text on large log files

I use the tail, head and grep commands to search log files. Most of the time the combination of these 3 commands, in addition to using pipe, gets the job done. However, I have this one log that many ...
2
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4answers
667 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
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5answers
1k 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 ...
1
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2answers
111 views

How to hide the . and .. from ls

When I run ls -l on a directory, I see an entry titled '.' How can I remove the row containing '.' from the output? ls -latr /foo | tail -n5 -rw-rw-r-- 1 guest bar 59169 Aug 20 12:22 ...
2
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1answer
1k views

Periodically get new lines from file, possibly logrotated

I'm looking for a fairly simple way (no development involved -- I could write this in Python but I'm hoping there's something already out there). I have a log file (in my case written by rsyslogd). ...
2
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3answers
711 views

Exception handling when using tail -f to monitor a log

I have a main script calling the script to do the monitoring. I am trying to catch the exception that the log is missing or not accessible anymore. tail -f is used instead of -F since the logs are ...
2
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2answers
143 views

whats a good tool to search tail -f output

I am dumping some debug info into a text file that I am using tail -f to monitor. Is there a tool that I can then pipe that tail -f data into to be able to search the text on screen using regular ...
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4answers
3k 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)
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2answers
3k views

Using tail to follow daily log file in Bash

I have a task to use a bash script to monitor a couple of log files named with the current day, eg. YYYY-MM-DD.log. (1) I used tail -f to follow the file but unable to deal file rotation. Even if ...
20
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4answers
9k views

How do I make Vim behave like “tail -f”?

I would like to know if there is a way to make Vim behave like tail -f. Even the best Vim plugin I've found so far doesn't do what I expect. I really want to see the file update in real-time. Even I'...
2
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1answer
2k views

Issue with real-time log inspecting piping tail, grep and cut

I have to inspect a growing log in real time, and I found an issue that makes me miss some lines (I can't understand exactly what lines) using tail -f or tailf, grep and cut. I use grep because I ...
6
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4answers
4k views

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

I'm usually inside GNU Screen or tmux, and that doesn't give me great scrolling functionality. Is there an alternative to tail -f that allows me to quickly scroll up? A tool that is like most is to ...
4
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1answer
264 views

How to follow and seek in a file being piped through a filter, in less

I basically wish to seek, search and follow a growing log file after passing it through a sed filter. I figured I need to follow a file with tail -f pipe it to sed and then pipe that to less. For ...
4
votes
1answer
1k views

tail -f but suck in content of the file first (aka `cat -f`)

I need to display whole file before tracking it for a new changes, not only the last 10 lines (yep, I know it's not tail conceptually). In other words, something like cat -f would do, if it would ever ...
3
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1answer
350 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 ...
2
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1answer
131 views

Making less's follow option show line movement

I often find myself using less to display log files that contain hundreds of contiguous, identical lines that are appended to the files at set intervals. For example, something happened something ...
12
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1answer
902 views

How to do `head` and `tail` on null-delimited input in bash?

find command can output names of files as a null-delimited strings (if -print0 is provided), and xargs can consume them with -0 option turned on. But in between, it's hard to manipulate that ...
0
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1answer
324 views

Tailing a New File with an Old Name [duplicate]

This is along the lines of How to start tailing a file that has not been yet created with a twist: a file with the name already exists. I have a program that is run multiple times; when the output ...
4
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0answers
83 views

Combing head and tail in a single call via pipe [duplicate]

On a regular basis, I am piping the output of some program to either head or tail. Now, suppose that I want to see the first AND last 10 lines of piped output, such that I could do something like ./...
0
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3answers
2k views

Using tail command to create a file

This is what I did using tail command. When I try to output the file to screen the file is empty. ~]$ tail > AFS2F1 PASSES ALL DATA FROM INPUT TO OUTPUT PASSES ONLY SPECIFIED COLUMNS PASSES NUMBER ...
4
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2answers
3k views

Tail -f piped through grep not outputing to file, but outputs to console

I'm using the following command tail -f /mydir/myfile | grep "searchterm" >> outfile Without the -f it works fine, but with the -f, which I need, nothing is written to the file. The ...
17
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4answers
4k views

How to do a continous 'wc -l' with gnu texttools?

I know of course that cat logfile.txt | wc -l 120 will tell me the number of lines in a file. Whereas tail -f logfile.txt will show me the new lines that another program writes to logfile.txt. ...
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2answers
13k views

How to use tail -f with grep to show surrounding lines

I would like to see the output in a logfile greped by only one domain but also the following two lines. Example: tail -f /var/log/apache2/modsec_audit.log |grep mydomain.de this shows all lines, ...
3
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1answer
320 views

Does multitail follow the inode or the file name by default?

For logrotated files one usually uses tail -F instead of tail -f to follow the log file contents. Does multitail(1) automatically follow the name instead of the inode (which likely changes with the ...
1
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3answers
263 views

How to view output for ALL processes simultaneously?

I know that you can connect to various background processes to watch their console output, but is there a way to view the output of all processes at once? Likely it would scroll quickly and be hard to ...
12
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1answer
7k views

Observe multiple log files in one output

Is there an easy way to do something like tail -f mylogfile but to have the changes of more than one file displayed (maybe with the file name added as prefix to each line)? Or maybe a GUI tool? I am ...
4
votes
3answers
10k views

How do I tail a log file and keep tailing it when the latest one changes date?

I'm using RHEL 4. The normal tail -F file_name*.log doesn't update when the time flips over to 0000. Here's what I've tried so far from searching the web, both of which try to use nested tail: ...
0
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3answers
535 views

Graphical logviewer that auto reload when file changes?

I'm wondering if there's a graphical viewer, also it needs to support auto-reloading when log file has changed. ksystemlog doesn't reload automatically.
5
votes
1answer
4k views

How to tail/grep/awk the last N bytes of a file, rather than lines

I have an application that is logging to a plain text log file (myapp.log) but it doesn't seem to be writing new line characters at the end of each log entry. If I execute a command like tail -n 50 ...
1
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2answers
2k views

$(tail) into variable removing \n

I am doing the following: x="Hello to the world of tomorrow\n <pre>"; x="${x}$(tail -n 50 log/logfile.log)" x="${x}</pre>"; echo -e $x | ./perlscript The Perl script: #!perl # ...
21
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9answers
41k 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. ...
3
votes
1answer
648 views

limit stdout to terminal output speed [duplicate]

Possible Duplicate: How can I limit the output speed of stdout? What's the easiest way to limit the speed at which stdout is output in a terminal, so that, for instance, tail -f outputs ...
9
votes
3answers
5k views

How can I do the equivalent of tail -f with ls? [duplicate]

Possible Duplicate: Is it possible to follow a command (run repeatedly)? as one would follow a file using tail -f? I would like to monitor files that are being downloaded to a directory in ...
59
votes
6answers
104k 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 /...
4
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1answer
4k views

Flush 'tail -f' buffer?

I'm using the following statement (simplified version): tail -f -c+1 <filename> in order to pipe a file to a process. What I've found, though, is that there is a number of lines at the end ...
21
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3answers
24k views

Piping from grep to awk not working

I am trying to grep the ongoing tail of file log and get the nth word from a line. Example file: $ cat > test.txt <<EOL Beam goes blah John goes hey Beam goes what? John goes forget it Beam ...