Why is `awk` printing a line from the first file?

Question

#!/bin/bash
awk 'FNR > 1 && NR==FNR {
  f_name = tolower($1) # first name
  l_name = tolower($2) # last name
  full_name = f_name":"l_name # full name used as array index
  address_city_county_state_zip = $4","$5","$6","$7","$8
  address[full_name] = address_city_county_state_zip
  next
  }
  {
    first_n = tolower($1) # first name
    last_n = tolower($2) # last name
    full_n = first_n":"last_n # full name used as array index
    printf ("%-10s %-10s %-55s %06.2f %-10s\n", $1, $2, address[full_n], $4, FILENAME)          
  }' $1 $2

./ch10_challenge.awk addresses.txt nameemailavg.tab

Input file nameemailavg.tab:

printf 'Art\tVenere\tart@venere.org\t256.62394383\nLenna\tPaprocki\tlpaprocki@hotmail.com\t259.688783099\nDonette\tFoller\tdonette.foller@cox.net\t282.32979844\n' > nameemailavg.tab

Input file addresses.txt:

printf 'first_name\tlast_name\tcompany_name\taddress\tcity\tcounty\tstate\tzip\tphone1\tphone2\temail\tweb\nAbel\tMaclead\tRangoni Of Florence\t37275 St  Rt 17m M\tMiddle Island\tSuffolk\tNY\t11953\t631-335-3414\t631-677-3675\tamaclead@gmail.com\thttp://www.rangoniofflorence.com\nArt\tVenere\tChemel, James L Cpa\t8 W Cerritos Ave #54\tBridgeport\tGloucester\tNJ\t08014\t856-636-8749\t856-264-4130\tart@venere.org\thttp://www.chemeljameslcpa.com\nDonette\tFoller\tPrinting Dimensions\t34 Center St\tHamilton\tButler\tOH\t45011\t513-570-1893\t513-549-4561\tdonette.foller@cox.net\thttp://www.printingdimensions.com\nSimona\tMorasca\tChapman, Ross E Esq\t3 Mcauley Dr\tAshland\tAshland\tOH\t44805\t419-503-2484\t419-800-6759\tsimona@morasca.com\thttp://www.chapmanrosseesq.com\nKiley\tCaldarera\tFeiner Bros\t25 E 75th St #69\tLos Angeles\tLos Angeles\tCA\t90034\t310-498-5651\t310-254-3084\tkiley.caldarera@aol.com\thttp://www.feinerbros.com\n' > addresses.txt

$ cat nameemailavg.tab
Art     Venere  art@venere.org  256.62394383
Lenna   Paprocki        lpaprocki@hotmail.com   259.688783099
Donette Foller  donette.foller@cox.net  282.32979844

$ cat addresses.txt
first_name      last_name       company_name    address city    county  state   zip     phone1  phone2  email   web
Abel    Maclead Rangoni Of Florence     37275 St  Rt 17m M      Middle Island   Suffolk NY      11953   631-335-3414    631-677-3675       amaclead@gmail.com      http://www.rangoniofflorence.com
Art     Venere  Chemel, James L Cpa     8 W Cerritos Ave #54    Bridgeport      Gloucester      NJ      08014   856-636-8749    856-264-4130       art@venere.org  http://www.chemeljameslcpa.com
Donette Foller  Printing Dimensions     34 Center St    Hamilton        Butler  OH      45011   513-570-1893    513-549-4561    donette.foller@cox.net     http://www.printingdimensions.com
Simona  Morasca Chapman, Ross E Esq     3 Mcauley Dr    Ashland Ashland OH      44805   419-503-2484    419-800-6759    simona@morasca.com http://www.chapmanrosseesq.com
Kiley   Caldarera       Feiner Bros     25 E 75th St #69        Los Angeles     Los Angeles     CA      90034   310-498-5651    310-254-3084       kiley.caldarera@aol.com http://www.feinerbros.com

Expected output:

| Art        | Venere     | James,L,Cpa,8,W                                         | 256.62 | nameemailavg.tab |
| ---- | ---- | ---- | --- | --- |
| Lenna      | Paprocki                                                           | 259.69 | nameemailavg.tab |
| Donette    | Foller     | Dimensions,34,Center,St,Hamilton                        | 282.33 | nameemailavg.tab |

The undesirable output is the first row with first_name, last_name, 000.00, last_name:

| first_name | last_name                                                          | 000.00 | addresses.txt |
| ---- | ---- | ---- | ---- | ---- |
| Art        | Venere     | James,L,Cpa,8,W                                         | 256.62 | nameemailavg.tab |
| Lenna      | Paprocki                                                           | 259.69 | nameemailavg.tab |
| Donette    | Foller     | Dimensions,34,Center,St,Hamilton                        | 282.33 | nameemailavg.tab |

Questions:

1. Why does my code print the first line from the file "addresses.txt"?
2. an awk program consists of a pattern { action }. Since lines 11-14 do not have a pattern and only an action, they are not executed because the previous block has next?
3. I updated the code block (10-15) to include the pattern FS="\t" so I can get to pattern { action } format. Unfortunately that had no impact.
4. When I reversed the call to awk like so, ./ch10_challenge.awk nameemailavg.tab addresses.txt, the output was messed up (expected), but the first line was from the file "nameemailavg.tab". In other words, whatever files is the first file, the output has that file as a 'header'.

Here is the revised code from the second block (line 10ff):

  FS = "\t" {
    first_n = tolower($1) # first name
    last_n = tolower($2) # last name
    full_n = first_n":"last_n # full name used as array index
    printf ("%-10s %-10s %-55s %06.2f %-10s\n", $1, $2, address[full_n], $4, FILENAME)          
  }' $1 $2

Answer 1

As Glenn said - add

NR == 1 {next}

at the top. FNR > 1 fails to match on the first record, so it doesn't hit the next in that section and is getting to the next block.

Answer 2

Questions with answers:

1. Why does my code print the first line from the file "addresses.txt"?

Because you put the FNR > 1 test in the wrong place and so the next is only executed after the first line of the first file.

2. an awk program consists of a pattern { action }. Since lines 11-14 do not have a pattern and only an action, they are not executed because the previous block has next?

"pattern" is an ambiguous, vague term - it's a condition, not a pattern, all of the existing documentation that says otherwise is misleading at best. So, awk scripts are a series of condition-action statements. Your code has a condition, the default one of "true", and so they are being executed - if they weren't you'd be getting no output since that second block is where your printf statement is.

3. I updated the code block (10-15) to include the pattern FS="\t" so I can get to pattern { action } format. Unfortunately that had no impact.

Doing that makes no sense. You added a condition that says "set FS to \t and if the result of that is that FS is not null, which it's not since it's \t, then execute the associated action". I don't know what impact you thought that might have.

4. When I reversed the call to awk like so, ./ch10_challenge.awk nameemailavg.tab addresses.txt, the output was messed up (expected), but the first line was from the file "nameemailavg.tab". In other words, whatever files is the first file, the output has that file as a 'header'.

Right. Whatever file you list first in the arguments is read first. Again, not sure what impact you thought swapping the input files might have if not that.

This is what your script is trying to do:

$ cat ./ch10_challenge
#!/usr/bin/env bash

awk '
    {
        first_n = tolower($1)           # first name
        last_n  = tolower($2)           # last name
        full_n  = first_n ":" last_n    # full name used as array index
    }
    NR==FNR {
        if ( FNR > 1 ) {
            address_city_county_state_zip = $4","$5","$6","$7","$8
            address[full_n] = address_city_county_state_zip
        }
        next
    }
    {
        printf "%-10s %-10s %-55s %06.2f %-10s\n", $1, $2, address[full_n], $4, FILENAME
    }
' "$1" "$2"

$ ./ch10_challenge addresses.txt nameemailavg.tab
Art        Venere     James,L,Cpa,8,W                                         256.62 nameemailavg.tab
Lenna      Paprocki                                                           259.69 nameemailavg.tab
Donette    Foller     Dimensions,34,Center,St,Hamilton                        282.33 nameemailavg.tab

Note that your script is a shell script, not an awk script, so adding a .awk suffix would not be appropriate.

Get the book Effective AWK Programming, 5th Edition, by Arnold Robbins to learn AWK.