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Full Discussion: awk, sed and a shell doubts
Top Forums Shell Programming and Scripting awk, sed and a shell doubts Post 302229617 by royalibrahim on Wednesday 27th of August 2008 10:21:25 AM
Old 08-27-2008
awk, sed and a shell doubts
Hi,

I have 3 doubts which I posted it here.

Doubt 1:
I have a file containing data:

22 -73 89 10
99 21 15 -77
23 63 -80 91
-22 65 28 97

I am trying to print the fields in the reverse order and replace every field by its absolute (positive) value
(ie.) I am looking for output:

10 89 73 22
77 15 21 99
91 80 63 23
97 28 65 22

when I use the following command

Code:
awk '{ for ( i = NF; i > 0; i-- ) if ($i < 0) $i = -$i; print $i }' <file>

it gives o/p

22 73 89 10
99 21 15 77
23 63 80 91
22 65 28 97

How do I get the output which I need?


Doubt 2:
what is the difference between the following 2 sed commands? And, also please explain the logic behind these commands, it's more obscure to understand.
It does remove all linefeed chars and make multiple lines into a single line.
Code:
sed ':a;$!{N;s/\n//;ba;}'
sed ':a;$!{N;ba;};$s/\n/ /g'


Doubt 3:
what is the difference between the following 2 shell commands?
I know they both sets the positional parameters to the values of $var
Code:
set $var  
set -- $var

 

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LEARN ABOUT NETBSD

set_color

set_color(1)							       fish							      set_color(1)

NAME

       set_color - set_color - set the terminal color

set_color - set the terminal color
   Synopsis
       set_color [-v --version] [-h --help] [-b --background COLOR] [COLOR]

   Description
       Change the foreground and/or background color of the terminal. COLOR is one of black, red, green, brown, yellow, blue, magenta, purple,
       cyan, white and normal.

       o -b, --background Set the background color

       o -c, --print-colors Prints a list of all valid color names

       o -h, --help Display help message and exit

       o -o, --bold Set bold or extra bright mode

       o -u, --underline Set underlined mode

       o -v, --version Display version and exit

       Calling set_color normal will set the terminal color to whatever is the default color of the terminal.

       Some terminals use the --bold escape sequence to switch to a brighter color set. On such terminals, set_color white will result in a grey
       font color, while set_color --bold white will result in a white font color.

       Not all terminal emulators support all these features. This is not a bug in set_color but a missing feature in the terminal emulator.

       set_color uses the terminfo database to look up how to change terminal colors on whatever terminal is in use. Some systems have old and
       incomplete terminfo databases, and may lack color information for terminals that support it. Download and install the latest version of
       ncurses and recompile fish against it in order to fix this issue.

Version 1.23.1							  Sun Jan 8 2012						      set_color(1)
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