Tagged Questions

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

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2
votes
1answer
966 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 ...
1
vote
4answers
243 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
4
votes
5answers
395 views

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

I have currently worked alot with shell and bash on linux. I have made tons of backups scripts and much more. In many cases I have a command that outputs thousands of lines. I actually need these ...
1
vote
2answers
88 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
votes
1answer
482 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
votes
3answers
369 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
votes
2answers
84 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 ...
1
vote
4answers
623 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)
3
votes
2answers
1k 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 ...
10
votes
4answers
2k 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 ...
2
votes
1answer
929 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 ...
3
votes
4answers
1k 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 ...
3
votes
1answer
137 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 ...
3
votes
2answers
269 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 ...
2
votes
1answer
168 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
votes
1answer
98 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 ...
11
votes
1answer
390 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
votes
1answer
130 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
votes
0answers
78 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
votes
3answers
636 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 ...
2
votes
2answers
932 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 ...
11
votes
4answers
1k 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. ...
3
votes
2answers
4k 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, ...
2
votes
1answer
177 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
vote
3answers
243 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 ...
5
votes
1answer
1k 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 ...
2
votes
3answers
2k 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
votes
3answers
331 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.
2
votes
1answer
1k 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 ...
0
votes
2answers
997 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 # ...
17
votes
8answers
17k 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
395 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 ...
4
votes
3answers
1k 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 ...
30
votes
5answers
42k 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
2k 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 ...
16
votes
3answers
6k 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 ...
6
votes
4answers
2k views

`tail -f` until text is seen

I've got a CI server with a command-line interface that allows me to remotely kick-off a job (jenkins CI server and the jenkins-cli.jar tool). After I kick the job off I tail -f the log (sorry for ...
7
votes
5answers
2k views

Output file contents while they change

I want to output a file's contents while they change, for example if I have the file foobar and I do: magic_command foobar The current terminal should display the file's contents and wait until, I ...
9
votes
1answer
995 views

How to have tail -f show colored output with vim?

In this question, Gilles answered Yet another possibility is to run tail -f in an Emacs shell buffer and use Emacs's syntax coloring abilities. Because I'm a vim user, I'd like to do this with ...
1
vote
2answers
710 views

Is there any other way to use tail -f for grep -q && operation?

I found this solution: http://stackoverflow.com/questions/7178888/grep-q-not-exiting-with-tail-f but is there any other possible? UPD: I want to do tail -f | grep -q something && echo ...
13
votes
3answers
3k 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 ...
8
votes
4answers
772 views

What is the easiest way to execute text from tail at the command line?

Sometimes I'm working on a new (ubuntu) box and I type git and am alerted: The program 'git' is currently not installed. You can install it by typing: apt-get install git-core If that happens I ...
11
votes
2answers
1k views

“tail -f | iconv -fsjis” does not output anything

I want to tail -f a file, but its content is in sjis encoding, so I need to have it converted to the native (utf-8) encoding of my terminal. When I do tail -f x | iconv -fsjis there will be no ...
3
votes
1answer
161 views

Why does tailing an output log sometimes give partial lines?

Sometimes, tailing an output log which is constantly being updated doesn't give the whole lines. Why is that? grep pattern input_file > output.log & tail output.log Why doesn't it print the ...
11
votes
2answers
220 views

How to start tailing a file that has not been yet created

I use tail to monitor the progress of jobs that I know will write their progress to disk. Almost always, I know which file they will create before they start running (the jobs are dispatched by a ...
19
votes
4answers
16k views

How to monitor only the last n lines of a log file?

I have a growing log file for which I want to display only the last 15 lines. Here is what I know I can do: tail -n 15 -F mylogfile.txt As the log file is filled, tail appends the last lines to the ...
4
votes
2answers
824 views

Moving average on a log file with awk or other unix utilities?

Scenario: I have a log file that has a few number of entry "classes", like this: R0 dx=0.00500 rb=0.00000 sn=1 3145.88 2.59 0.08 se=21315 id=16190 R0 dx=0.00300 rb=-1.00000 sn=1 3150.40 2.38 0.05 ...
3
votes
3answers
447 views

How to make dot matrix printer print every line of 'tail -f'

I have a dot matrix printer, an Epson LQ-500. It works well with CUPS, and I use it to print listings sometimes, text files, etc. now, I'd like to use it as a logging printer. for that, I need it to ...
7
votes
3answers
2k views

Follow a pipe using less?

Can less follow (by pressing F) a piped input (similarly to a file)? For a file that is being written to, the command less <file> will follow the file when pressing F. But if I have a ...
3
votes
2answers
91 views

Output the changes to a log file

If I use tail -f *filename* I get a real nice display of whatever is changing in a given file. However, sometimes I want to be able to search this text or otherwise look it over slowly. Is ...