space-asterisk in bash killed my server Post: 302348593

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Top Forums UNIX for Dummies Questions & Answers space-asterisk in bash killed my server Post 302348593 by treesloth on Friday 28th of August 2009 04:24:28 PM

08-28-2009

Registered User

space-asterisk in bash killed my server

So, here's the deal... I was attempting to type this:

Code:

>  grep -R "searchterm" *

and somehow I typed this instead:

Code:

>  grep -R "searchterm"

>   *

I accidentally typed "space-asterisk" on the second prompt. This apparently caused Bash to attempt to run the first file in the pwd, which happened to have *something* that spawned a load of processes and killed my server (a VPS with fixed process count). I've never seen this. Can anyone explain the "space-asterisk" phenomenon? It seems like the sort of thing that's a subset of a bigger form of command line trickery and awesomeness, but I can't seem to put together the right search terms to get Dr. Google to explain it to me...

treesloth

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LEARN ABOUT OSX

ppmtosixel

ppmtosixel(1)						      General Commands Manual						     ppmtosixel(1)

NAME

       ppmtosixel - convert a portable pixmap into DEC sixel format

SYNOPSIS

       ppmtosixel [-raw] [-margin] [ppmfile]

DESCRIPTION

       Reads  a  portable  pixmap  as input.  Produces sixel commands (SIX) as output.	The output is formatted for color printing, e.g. for a DEC
       LJ250 color inkjet printer.

       If RGB values from the PPM file do not have maxval=100, the RGB values are rescaled.  A printer control header and a color assignment table
       begin the SIX file.  Image data is written in a compressed format by default.  A printer control footer ends the image file.

OPTIONS

       -raw   If  specified,  each  pixel  will  be explicitly described in the image file.  If -raw is not specified, output will default to com-
	      pressed format in which identical adjacent pixels are replaced by "repeat pixel" commands.  A raw file is often an order	of  magni-
	      tude larger than a compressed file and prints much slower.

       -margin
	      If  -margin  is not specified, the image will be start at the left margin (of the window, paper, or whatever).  If -margin is speci-
	      fied, a 1.5 inch left margin will offset the image.

PRINTING

       Generally, sixel files must reach the printer unfiltered.  Use the lpr -x option or cat filename > /dev/tty0?.

BUGS

       Upon rescaling, truncation of the least significant bits of RGB values may result in poor color conversion.  If the original PPM maxval was
       greater	than  100,  rescaling  also reduces the image depth.  While the actual RGB values from the ppm file are more or less retained, the
       color palette of the LJ250 may not match the colors on your screen.  This seems to be a printer limitation.

SEE ALSO

       ppm(5)

AUTHOR

       Copyright (C) 1991 by Rick Vinci.

								   26 April 1991						     ppmtosixel(1)