csvfind.c

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "csv.h"

char *city = "test";
int row_index = 0;

void data_callback(void *string, size_t i, void *data) {
    if (row_index == 1 && strncmp(city, string, strlen(city)) == 0) {
        printf("found\n");
    }
    row_index++;
}

void row_callback(int c, void *data) {
    row_index = 0;
}

int main(int argc, char **argv) {
    if (argc > 0) {
        city = argv[1];
    }

    struct csv_parser parser;
    char buf[1024];
    size_t bytes_read;

    csv_init(&parser, 0);
    while (1) {
        bytes_read = fread(buf, 1, 1024, stdin);
        if (bytes_read > 0) {
            if (csv_parse(&parser, buf, bytes_read, data_callback, row_callback, NULL) != bytes_read) {
                fprintf(stderr, "Error: %s\n", csv_strerror(csv_error(&parser)));
                exit(EXIT_FAILURE);
            }
        }
        if (bytes_read != 1024) {
            break;
        }
    }

    csv_fini(&parser, data_callback, row_callback, NULL);
    csv_free(&parser);
    return EXIT_SUCCESS;
}

csvfind.js

var csv = require('csv');

process.stdin.resume();
process.stdin.setEncoding('utf8');

var city = process.argv[2];

csv()
    .from.stream(process.stdin)
    .on('record', function(row, index) {
        if (row[1] == city) {
            console.log(JSON.stringify(row));
        }
    });

csvfind.py

import csv
import sys

reader = csv.reader(sys.stdin)
city = sys.argv[1]
for row in reader:
    if row[1] == city:
        print row

results.md

$ time gzcat ~/Downloads/worldcitiespop.txt.gz | node csvfind.js "lake dallas"

["us","lake dallas","Lake Dallas","TX","","33.1191667","-97.0252778"]
gzcat ~/Downloads/worldcitiespop.txt.gz  0.45s user 0.04s system 2% cpu 24.880 total
node csvfind.js "lake dallas"  24.89s user 0.16s system 100% cpu 24.901 total

$ time gzcat ~/Downloads/worldcitiespop.txt.gz | python csvfind.py "lake dallas"
['us', 'lake dallas', 'Lake Dallas', 'TX', '', '33.1191667', '-97.0252778']
gzcat ~/Downloads/worldcitiespop.txt.gz  0.43s user 0.03s system 16% cpu 2.742 total
python csvfind.py "lake dallas"  2.67s user 0.03s system 98% cpu 2.745 total

$ time gzcat ~/Downloads/worldcitiespop.txt.gz | ./csvfind "lake dallas"
found
gzcat ~/Downloads/worldcitiespop.txt.gz  0.43s user 0.04s system 55% cpu 0.835 total
./csvfind "lake dallas"  0.82s user 0.01s system 99% cpu 0.834 total