meaning of ${0%${0##*/}} Post: 302238841

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Operating Systems AIX meaning of ${0%${0##*/}} Post 302238841 by bakunin on Monday 22nd of September 2008 06:51:17 AM

09-22-2008

Registered User

Quote:

Originally Posted by nyelavarthy

. ${0%${0##*/}}Script2 or . ./Script2

Both do the same job. then why use this ". ${0%${0##*/}}Script2" instead of simply using ". ./Script2"?

In this case they expand to the same value, but that has not always to be the case. Suppose the following: you call your script not from the directory where it is stored but from somewhere else:

Code:

$ cd /some/dir
$ /some/other/dir/script
$ _

inside your script the "./" will expand to the PWD, which is not where the script is stored but where you have been when starting the script - "/some/dir" in the example, not "/some/other/dir". If you now execute

Code:

. ./script2

you will execute "/some/dir/script2" instead of "/some/other/dir/script2". Still $0 will contain "/some/other/dir/script" and subsequently the expansion will find script2 on its correct place.

As a rule of thumb: avoid relative paths like the plague in scripts. Always use absolute paths to make sure you end up where you suppose to end up.

I hope this helps

bakunin

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LEARN ABOUT DEBIAN

exrpptm

exrpptm(1)						      General Commands Manual							exrpptm(1)

NAME

       exrpptm - performs tone mapping on an OpenEXR image (photoreceptor)

SYNOPSIS

       exrpptm [options] input.exr output.exr

DESCRIPTION

       Performs the tone mapping function described in this paper:

       Erik  Reinhard and Kate Devlin.	Dynamic Range Reduction Inspired by Photoreceptor Physiology.  IEEE Transactions on Visualization and Com-
       puter Graphics (2004).

       The input image should be normalized, and the output file returned by this function should also be normalized before viewing.

OPTIONS

       -f     Controls the intensity of the resulting image.  Valid range is from -8 to 8, defaulting to 0.

       -m     Controls the contrast of the resulting image.  Valid range is from 0.3 to 1.0.  The default value of 0 uses an algorithm	to  calcu-
	      late an appropriate m factor for the image based on its luminance.

       -c     Amount  of  chromatic  adaptation  to  apply to the image.  Valid range is from 0 meaning no chromatic adaptation to 1 meaning fully
	      adapted.	Defaults to 0.

       -a     Controls the light adaptation.  Valid range is from 0 meaning that the adaptation is global to 1	meaning  that  the  adaptation	is
	      based on pixel intensity.  Defaults to 1, to trade detail visibility for contrast.

AUTHORS

       Billy Biggs <vektor@dumbterm.net>.

SEE ALSO

       exrtools(1).

exrtools 0.4							   December 2003							exrpptm(1)

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