11-26-2012
p1 is used to store the value of the first field. Since this is done at the end of each line processing, it becomes the previous value of the first field for the current line.
Quote:
Is prev a built-in variable?
No. In
awk, the built-in variables are all upper-case words.
prev is used to store the line made up by appending segments of the lines which have common first fields. After printing each made-up line, we need to nullify the variable to make it ready for the next line to be made up.
And the cryptic line does what you thought it does. If
prev"" (
prev is not-null) is true, then we must be having at least 1 line in
prev so we need to append a
, (
FS - field separator, comma in this case, and that's a special/built-in
awk variable) and the substring of the line from the second field onwards. Else if
prev is null, then it must be the first time since printing the last
prev. So, just assign the current line (
$0) to
prev.
And, I think you've understood rest of the things.
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IGAWK(1) Utility Commands IGAWK(1)
NAME
igawk - gawk with include files
SYNOPSIS
igawk [ all gawk options ] -f program-file [ -- ] file ...
igawk [ all gawk options ] [ -- ] program-text file ...
DESCRIPTION
Igawk is a simple shell script that adds the ability to have ``include files'' to gawk(1).
AWK programs for igawk are the same as for gawk, except that, in addition, you may have lines like
@include getopt.awk
in your program to include the file getopt.awk from either the current directory or one of the other directories in the search path.
OPTIONS
See gawk(1) for a full description of the AWK language and the options that gawk supports.
EXAMPLES
cat << EOF > test.awk
@include getopt.awk
BEGIN {
while (getopt(ARGC, ARGV, "am:q") != -1)
...
}
EOF
igawk -f test.awk
SEE ALSO
gawk(1)
Effective AWK Programming, Edition 1.0, published by the Free Software Foundation, 1995.
AUTHOR
Arnold Robbins (arnold@skeeve.com).
Free Software Foundation Nov 3 1999 IGAWK(1)