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Homework and Emergencies Emergency UNIX and Linux Support Find a line using a condition and replace a string in that line Post 302581915 by Corona688 on Wednesday 14th of December 2011 10:48:47 AM
Old 12-14-2011
That looks like a fine illustration of awk's basic principles actually Smilie I'll just comment it a bit more:

Code:
# awk code blocks work like CONDITION { code } WHENTOPRINT
# For each line, { code } gets run when CONDITION is true
# and the line gets printed back out when WHENTOPRINT is true.
# The code block doesn't have to be executed for WHENTOPRINT to
# cause it to print a line.
#
# CONDITION is default true if not given.  WHENTOPRINT is default false.

awk '
# Special code section run before any lines are read
BEGIN {
        # Field separator.  It defaults to whitespace but can be anything.
        # Lines read get split on it, put into special variables $1,$2,...
        # all the way up to NF, the last field.  NF is the number, $NF is the
        # last field itself.  $0 is the entire line.
        # ( $ is an operator, by the way.  You can do N=1; print $N to print field 1)
        FS="*"
        # When the 'print' command is used, awk puts the line back
        # together from the $1,$2,...$NF fields before printing it, you can
        # control what it joins together fields with.
        OFS="*"}

# The code block gets run whenever the regex /^ABC/ is true --
# i.e. whenever the line begins with ABC.
/^ABC/ {
        # You can set fields, not just read them, handy for altering text
        # On the go.  Here, we change the 7th field into 13 for any line
        # beginning with ABC.
        $7="13";
        # You can also tell awk when to print explicitly, by using the 'print'
        # command.  By default it prints out the entire line assembled from
        # the current contents of $1,$2,...$NF
        print }' filename


Last edited by Corona688; 12-14-2011 at 11:54 AM..
This User Gave Thanks to Corona688 For This Post:
 

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COLORS(3)						   libbash colors Library Manual						 COLORS(3)

NAME
colors -- libbash library for setting tty colors. SYNOPSIS
colorSet <color> colorReset colorPrint [<indent>] <color> <text> colorPrintN [<indent>] <color> <text> DESCRIPTION
General colors is a collection of functions that make it very easy to put colored text on tty. The function list: colorSet Sets the color of the prints to the tty to COLOR colorReset Resets current tty color back to normal colorPrint Prints TEXT in the color COLOR indented by INDENT (without adding a newline) colorPrintN The same as colorPrint, but trailing newline is added Detailed interface description follows. Available colors: Green Red Yellow White The color parameter is non-case-sensitive (i.e. RED, red, ReD, and all the other forms are valid and are the same as Red). FUNCTIONS DESCRIPTIONS
colorSet <color> Sets the current printing color to color. colorReset Resets current tty color back to normal. colorPrint [<indent>] <color> Prints text using the color color indented by indent (without adding a newline). Parameters: <indent> The column to move to before start printing. This parameter is optional. If ommitted - start output from current cursor position. <color> The color to use. <color> The text to print. colorPrintN [<indent>] <color> The same as colorPrint, except a trailing newline is added. EXAMPLES
Printing a green 'Hello World' with a newline: Using colorSet: $ colorSet green $ echo 'Hello World' $ colorReset Using colorPrint: $ colorPrint 'Hello World'; echo Using colorPrintN: $ colorPrintN 'Hello World' AUTHORS
Hai Zaar <haizaar@haizaar.com> Gil Ran <gil@ran4.net> SEE ALSO
ldbash(1), libbash(1) Linux Epoch Linux
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