Query on decision making... Post: 302475616

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Top Forums Shell Programming and Scripting Query on decision making... Post 302475616 by frans on Monday 29th of November 2010 09:39:44 AM

11-29-2010

Registered User

Quote:

Originally Posted by biglau

That's right, but why [[ ]] does not support `` ?

As your function has all its outputs redirected to /dev/null, it outputs nothing.
so the test [[ `is_number 0100` ]] is interpreted as [[ ]] with nothing inside.

By the way, the function could be written: is_number() { echo $1 | egrep -q '^[1-9][0-9]*$'; }

The -q (quiet) option removes output
The return code of the function is the return code of the last command in it

---------- Post updated at 15:39 ---------- Previous update was at 15:35 ----------

Quote:

Originally Posted by biglau

bro, what if I need to put multiple conditions in an if statement without using the brackets?
like:
if is_number $3 || $# -ne 3

Tthe first part doesn't need test (where the brackets stand for) bur the second, yes. Youi should write

Code:

if is_number $3 || [ $# -ne 3 ]
# or using arithmetic evaluation
if is_number $3 || (( $# != 3 ))

frans

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------- Output Screen -------- Choose the option ----------------- 1.Input 2.Output 3.CFT Uniq x.Exit ----------------- 2 Enter the Output flow IDF PBL5572U Enter the Output existing flow IDF PBL5198H sf_PBL5572U.cmd file exist in invalid path or doesn't exist

LEARN ABOUT SUNOS

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)