01-30-2008
Perl onliner to search the last line with an occurence of a pattern
Hi
I need a perl onliner which seaches a line starting with a pattern(last occurence) and display it.
similar to
grep 'pattern' filename | tail -1 in UNIX
Ex: I want to display the line starting with "cool" and which is a last occurence
adadfadafadf
adfadadf
cool dfadfadfadfara
adfadfadf
cool aaaaaaaaaaaaaa
hai how are you
It should dispaly the line which is red. I need it in perl one line command
I am not sure how i should do. I have an idea that we can do it with
perl -ne 'print .........
Your help will be highly appreciated
Thanks
Ammu
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LEARN ABOUT DEBIAN
root-tail
ROOTTAIL(1) General Commands Manual ROOTTAIL(1)
NAME
root-tail - print text directly to X11 root window
SYNOPSIS
root-tail [-g|--geometry GEOMETRY] [-fn|--font FONTSPEC] [--color color] [--reload SEC COMMAND] [--shade] [--outline] [--minspace]
[--noflicker] [-f|--fork] [--reverse] [--whole] [--partial] [--update] [--cont STRING] [--wordwrap] [--justify] [--noinitial] [--frame]
[-id ID] [-i|--interval SECONDS] [-V] file1[,color[,desc]] [file2[,color[,desc]]]
DESCRIPTION
Displays a given file anywhere on your X11 root window, i.e. it is kind of tail -f for multiple files using your desktop background as out-
put window.
All non-option arguments on the command line are files to be logged. A null desc (example: "/var/log/messages,red,") will prevent the
printing of a description and the []'s.
General Options
--color COLOR
Use COLOR as default.
--font | -fn FONTSPEC
Use font FONTSPEC. This can be either a fixed width font like -fn fixed or any font using -fn '-*-*-*-*-*-*-*-*-*-*-*-*-*-*' with
the appropriate fields filled out (see xfontsel). Specifying a different FONTSPEC before each filename will cause each file to be
displayed in a different font.
-f | --fork
Forks to the background.
--reverse
Display the files in reverse order, with the newest lines at the top.
--whole
Only display whole lines. If the last line of a file doesn't yet end with a newline character then wait until it does before dis-
playing it. This is the default if more than one file is being displayed.
--partial
This is the opposite of the --whole option (see above). It displays lines even if they don't yet have a newline at the end. This is
the default if only one file is being displayed.
--update
Update partial lines 'in place' if they are still on the screen when they are updated in their files. Using --update automatically
turns on --partial.
--cont STRING
When partial lines are broken into two lines in the display, prefix the 2nd line with STRING. Defaults to "|| ". Specify the
"--whole" argument to ensure partial lines are never displayed, or specify "--update" to attempt to "repair" broken lines in-place.
--cont-color COLOR
Use COLOR when displaying the continuation string (as optionally specified with the --cont option above).
--wordwrap
The default behaviour is to fit as much as possible onto each line of output, even if this means splitting a word between one line
and the next. The --wordwrap argument splits lines at spaces if possible.
--justify
After wrapping long lines, attempt to justify the text to produce a smooth right-hand margin. Implies --wordwrap.
--reload SEC COMMAND
Re-display the file(s) and run COMMAND every SEC seconds. The default is to never re-display the file(s).
--shade
Add black shading to the font.
--outline
Add a black outline to the font (making redraws quite a bit slower).
--minspace
Use minimum linespace even when using shading or outlining. This might result in leftover pixels (dependign on font and logfile con-
tent).
--noflicker
Use slower but flicker-free update.
--noinitial
Don't display the end of the file(s) initially.
-id ID Use the given window ID for output instead of the root window.
-i | --interval SECONDS
Use the specified sleeping interval between checks instead of the default 2.4 seconds. Fractional values are OK.
-V Print version information.
--frame
Draw a frame around the selected area. This is useful when trying to find the perfect geometry.
EXAMPLE
root-tail -g 800x250+100+50 -font 10x20 /var/log/messages,green -font 12x24 /var/log/secure,red,'ALERT'
BUGS
Some desktop environments open a virtual root window and make it difficult to share it. If you cannot see anything after starting root-
tail, try to find a setting "allow programs on desktop" or similar, or manually specify a window id.
Should you happen to find any bugs please fix them and send me a diff.
NOTE: This program was modified by Marc Lehmann <pcg@goof.com>, who couldn't reach the original author. Please direct bug-reports etc. to
pcg@goof.com.
http://root-tail.plan9.de/
4.2 Berkeley Distribution 2004-03-27 ROOTTAIL(1)