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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LEARN ABOUT CENTOS
tzselect
TZSELECT(8) Linux System Administration TZSELECT(8)
NAME
tzselect - select a timezone
SYNOPSIS
tzselect
DESCRIPTION
The tzselect program asks the user for information about the current location, and outputs the resulting timezone description to standard
output. The output is suitable as a value for the TZ environment variable.
All interaction with the user is done via standard input and standard error.
EXIT STATUS
The exit status is zero if a timezone was successfully obtained from the user, nonzero otherwise.
ENVIRONMENT
AWK Name of a Posix-compliant awk program (default: awk).
TZDIR Name of the directory containing timezone data files (default: /usr/share/zoneinfo).
FILES
TZDIR/iso3166.tab
Table of ISO 3166 2-letter country codes and country names.
TZDIR/zone.tab
Table of country codes, latitude and longitude, TZ values, and descriptive comments.
TZDIR/TZ
Time zone data file for timezone TZ.
SEE ALSO
tzfile(5), zdump(8), zic(8)
COLOPHON
This page is part of release 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
2007-05-18 TZSELECT(8)