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#!/usr/bin/mawk -We
# *********************************************************************
# Written by and copyright Carlo Strozzi <carlos@linux.it>.
#
# rmcolumn: remove selected columns from a NoSQL table.
# Copyright (C) 1998-2001 Carlo Strozzi <carlos@linux.it>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
#
# 2001-01-03 Ported to NoSQL v3
# 2001-04-17 Added inline help
# 2001-08-17 Added stdio portability
#
# $Id$
# *********************************************************************
BEGIN {
NULL = ""; FS = OFS = "\t"
while (ARGV[++i] != NULL) {
if (ARGV[i] == "-N" || ARGV[i] == "--no-header") no_hdr = 1
else if (ARGV[i] == "-i" || ARGV[i] == "--input") i_file = ARGV[++i]
else if (ARGV[i] == "-o" || ARGV[i] == "--output") o_file = ARGV[++i]
else if (ARGV[i] == "-h" || ARGV[i] == "--help") {
system("grep -v '^#' @DOCPATH@/rmcolumn.txt")
rc = 1
exit(rc)
}
else command_cols[++j] = ARGV[i]
}
ARGC = 1 # Fix argv[]
if (o_file == NULL) o_file = "@STDOUT@"
if (i_file != NULL) { ARGV[1] = i_file; ARGC = 2 }
}
NR == 1 {
# Start building the back-end awk program.
awkpgm = "'BEGIN{FS=OFS=\"\\t\";}"
# Load the column position array.
while (++p <= NF) {
# Make sure we pick the first occurrence of duplicated column
# names (it may happen after a join).
if (P[$p] == NULL) { P[$p] = p; N[p] = $p; good_cols++ }
}
# Now remove unwanted columns.
for (i in command_cols) {
if (P[command_cols[i]] != NULL) {
delete P[command_cols[i]]
# Exit if all columns have been removed.
if (--good_cols == 0) exit
}
}
# Build the list of columns, in awk format.
for (i = 1; i <= NF; i++) {
if (P[$i] != NULL) {
out_rec = out_rec OFS $i
fieldlist = fieldlist $i "=$(" P[$i] ");"
out_list = out_list "," $i
}
}
# Remove leading extra comma from out_list.
sub(/^,/, NULL, out_list)
# Remove leading extra OFS from out_rec, then print header and dashline.
if (!no_hdr) {
sub(/^\t/, "", out_rec); print out_rec > o_file
gsub(/[^\t]/, "-", out_rec); print out_rec > o_file
}
# Make sure the header is printed before calling mawk(1) again.
fflush()
# Close output file before the back-end mawk(1) appends to it.
if (o_file != "@STDOUT@") close(o_file)
awkpgm = awkpgm "{" fieldlist "print " out_list ";}'"
unix_cmd = "mawk " awkpgm
next
}
# Dashline
NR == 2 {
# Let's save one concurrent process and a couple of msec.
unix_cmd = "exec " unix_cmd
if (o_file != "@STDOUT@") unix_cmd = unix_cmd " >> " o_file
next
}
{ print | unix_cmd }
END {
if (rc) exit(rc)
exit(close(unix_cmd)) # Return back-end mawk(1) exit status
}
#
# End of program
#
|
