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Full Discussion: Bash syntax
Top Forums Shell Programming and Scripting Bash syntax Post 302919705 by gull04 on Friday 3rd of October 2014 08:52:37 AM
Old 10-03-2014
Hi,

Over the years I have seen this syntax several times, in a case like this it is down to the user to chose the appropriate text.

As an example, a piece of testing code we use. The code is used to attempt to grab all the process table resource on a virtual system.

Code:
fork_proc() { fork_proc XX fork_proc & } ; fork_proc

The code,

Code:
fork_proc()

Is the routine definition, followed by what the code actually does in the braces. In this case, run a process - pass the output to the process and put it in the background.

Code:
{ fork_proc XX fork_proc & }

Followed by the commad it's self.

Code:
; fork_proc

Could just as easilly be written as,

Code:
:(){ : XX :& };:

We use the above as a test to ensure that solaris zones are correctly configures, this is one of several routines used to ensure that the zone has a correctly configured process table and that it won't impact the performance of a global zone.


Regards

Dave
This User Gave Thanks to gull04 For This Post:
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LEARN ABOUT LINUX

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)
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