Commands tagged tail

Realtime lines per second in a log file using python ... identical to perl version, except python is much better :)

This is a little trickier than finding the last Sunday, because you know the last Sunday is in the first position of the last line. The trick is to use the NF less than or equal to 7 so it picks up all the lines then grep out any empty lines.

This is a function that implements an improved version of tail. It tries to limit the number of lines so that the screen is filled completely. It works with pipes, single and multiple files. If you add different options to tail, they will overwrite the settings from the function.

It doesn't work very well when too many files (with wrapped lines) are specified.

Its optimised for my three-line prompt.

It also works for head. Just s/tail/head/g

Don't set 'thbin="tail"', this might lead to a forkbomb.

Run the alias command, then issue

and resize your terminal window (putty/console/hyperterm/xterm/etc) then issue the same command and you'll understand.

Insructs the shell that if LINES is not set or null to use the output from `tput lines` ( ncurses based terminal access ) to get the number of lines in your terminal. But furthermore, in case that doesn't work either, it will default to using the default of 80.

The default for TAIL is to output the last 10 lines, this alias changes the default to output the last x lines instead, where x is the number of lines currently displayed on your terminal - 7. The -7 is there so that the top line displayed is the command you ran that used TAIL, ie the prompt.

Depending on whether your PS1 and/or PROMPT_COMMAND output more than 1 line (mine is 3) you will want to increase from -2. So with my prompt being the following, I need -7, or - 5 if I only want to display the commandline at the top. ( http://www.askapache.com/linux/bash-power-prompt.html )

275MB/748MB

[7995:7993 - 0:186] 06:26:49 Thu Apr 08 [askapache@n1-backbone5:/dev/pts/0 +1] ~

In most shells the LINES variable is created automatically at login and updated when the terminal is resized (28 linux, 23/20 others for SIGWINCH) to contain the number of vertical lines that can fit in your terminal window. Because the alias doesn't hard-code the current LINES but relys on the $LINES variable, this is a dynamic alias that will always work on a tty device.

This will quickly display files last changed in a directory, with the newest on top.

List all files in a directory in reverse order by modified timestamp. When piped through tail the user will see the most recent file name.

this way you have the multitail with all its options running on your own machine with the tails of the two remote machines inside :)

Tail is much faster than sed, awk because it doesn't check for regular expressions.

like #9295, but awkish instead of perlish

say only processes a complete file, at eof, so following a file isn't possible. Quick and dirty perl oneliner to feed each line from the tail -f to say. Yes, expensive to lauch a new process each line.

This little ditty was prompted by a discussion on how horrible it is to use VoiceOver on ncurses programs such as irssi.

Using tail to follow and standard perl to count and print the lps when lines are written to the logfile.

You can actually do the same thing with a combination of head and tail. For example, in a file of four lines, if you just want the middle two lines:

Line 1 --\

being printed to screen (or wherever you redirect it).

Uses history to get the last n+1 commands (since this command will appear as the most recent), then strips out the line number and this command using sed, and appends the commands to a file.

Yep, now you can finally google from the command line!

Here's a readable version "for your pleasure"(c):

Enjoy :)

Should be a bit more portable since echo -e/n and date's -Ins are not.

This is useful when watching a log file that does not contain timestamps itself.

If the file already has content when starting the command, the first lines will have the "wrong" timestamp when the command was started and not when the lines were originally written.

tail -c 1 "$1" returns the last byte in the file.

Command substitution deletes any trailing newlines, so if the file ended in a newline $(tail -c 1 "$1") is now empty, and the -z test succeeds.

However, $a will also be empty for an empty file, so we add -s "$1" to check that the file has a size greater than zero.

Finally, -f "$1" checks that the file is a regular file -- not a directory or a socket, etc.

Tail all logs that are opened by all java processes. This is helpful when you are on a new environment and you do not know where the logs are located. Instead of java you can put any process name. This command does work only for Linux.

The list of all log files opened by java process:

Another way of counting the line output of tail over 10s not requiring pv.

Cut to have the average per second rate :

tail -n0 -f access.log>/tmp/tmp.log & sleep 10; kill $! ; wc -l /tmp/tmp.log | cut -c-2

You can also enclose it in a loop and send stderr to /dev/null :

while true; do tail -n0 -f access.log>/tmp/tmp.log & sleep 2; kill $! ; wc -l /tmp/tmp.log | cut -c-2; done 2>/dev/null