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Top Forums Shell Programming and Scripting Problem with occurence of square brackets Post 302905600 by neutronscott on Thursday 12th of June 2014 10:08:35 AM
Old 06-12-2014
Yes, sorry. It's just clever escaping. Like one would ps | grep [s]omething. I began to use this more because in awk, depending on quoting/context, often times you need to escape your escapes since they're really processed twice, and it gets ugly so I tend to avoid \ when possible now. Smilie

Quote:
Originally Posted by Scrutinizer
And NeutronScott's approach..
Code:
sed 's/[^[]*[[]\([^]]*\)]\(\[.*\]\)*/\1 --/' file

(the original will fail with more than two square bracket episodes)
The * after the grouping allows it to repeat. But I see mine doesn't perform correctly in the last two cases.

Code:
mute@thedoctor:~$ cat input
this is spam [i need this][this is spam][another one][last] and i need this too
this is spam [i need this] probably everything [here] too
this is spam [i need this] and probably i need ] everything here too?
mute@thedoctor:~$ sed 's/[^[]*[[]\([^]]*\)]\([[][^]]*]\)*\([^]]*\)$/\1 -- \3/g' input
i need this --  and i need this too
this is spam [here --  too
this is spam [i need this] and probably i need ] everything here too?
mute@thedoctor:~$ sed 's/[^[]*[[]\([^]]*\)]\(\[.*\]\)*/\1 --/' input
i need this -- and i need this too
i need this -- probably everything [here] too
i need this -- and probably i need ] everything here too?

I also didn't think of not needing to match & sub the last part. That's definitely shorter.
 

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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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