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Top Forums Shell Programming and Scripting awk variables in regex expression ? Post 302486124 by michaelrozar17 on Friday 7th of January 2011 04:48:10 AM
Old 01-07-2011
Quote:
Originally Posted by vilius
Hello,

Could someone explain why this one returns nothing:
Code:
$ x=/jon/
$ echo jon | awk -v xa=$x '$1~xa {print}'
$

When a pattern matching is done using ~ we need to give the reg-exp in between / / (2 forward slashes).Still, when given inside the slashes it is taken as literally, so when changing the above awk as
Code:
echo jon | awk -v xa=$x '$1~/xa/ {print}'

it matches the word xa and not the variable xa's value.Hence we need to expand the variable as below
Code:
x=/jon/
echo jon | awk -v xa=$x '$1~/'"$xa"'/ {print}'

This is not the case when == is used as you would know this is used to equate between variables.Therefore in code $1==xa.. xa is expanded (to jon).
 

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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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