CODEWITHSUNDEEP
bashawk
colt
colt

Reputation: 15

awk pattern match - substr field action issue

I call on Windows a list of datafiles in this way:

gawk -f datetab.awk datetab*.csv

All data files look mainly the same like datatab1.csv. But have in mind this is exemplary. Important is that there is an unknown number before and after the record start. We need all records after start. Here time stamps are shown in two different columns ($2 & $3). $2 timestamps shall be shortened / reformatted to DD.MM.YYYY

1st datafile / input

Rec not needed  Rec not needed  Rec not needed
Rec not needed  Rec not needed  Rec not needed
start       
    10-12-2014 06:47:59 10-12-2014 06:47:59
    11-12-2014 10:17:44 11-12-2014 10:17:44
    12-12-2014 10:37:44 12-12-2014 10:37:44
    13-12-2014 10:00:32 13-12-2014 10:00:32

The fields are delimited by tab.

sourcefile datetab.awk is this:

BEGIN { FS=OFS="\t"}
FNR==1     {p=0}

$2=substr($2,1,11)   # shorten date to DD-MM-YYYY
gsub(/-/,".",$2)     # replace - by . --> DD.MM.YYYY
# (x=index($2," ") > 0) {
#   DDMMYY = substr($2,1,x-1);
#};

p!=0{print};
/start/{p=1}

At the point there is the line $2=substr($2,1,11) in the sourcefile the pattern matching /start/ is broken. why?

output should be this:

10.12.2014 10-12-2014 06:47:59
11.12.2014 11-12-2014 10:17:44
12.12.2014 12-12-2014 10:37:44
13.12.2014 13-12-2014 10:00:32

In my case with the given code I got negation of the /start/ pattern and some sort of dublication. The sbustr and gsub action add lines. I found the pattern matching "print from line X" for each file of a list of datafiles here in this forum. I do not understand why it is not working. please explain to me how to work with awk on a list of datafiles with some rudimentary field manipulation after a pattern-matching /start/.

Rec not needed  Rec not nee     Rec not needed
Rec not needed  Rec not nee     Rec not needed
Rec not needed  Rec not nee     Rec not needed
Rec not needed  Rec not nee     Rec not needed
        10-12-2014      10-12-2014 06:47:59
        10.12.2014      10-12-2014 06:47:59
        10.12.2014      10-12-2014 06:47:59
        11-12-2014      11-12-2014 10:17:44
        11.12.2014      11-12-2014 10:17:44
        11.12.2014      11-12-2014 10:17:44
        12-12-2014      12-12-2014 10:37:44
        12.12.2014      12-12-2014 10:37:44
        12.12.2014      12-12-2014 10:37:44
        13-12-2014      13-12-2014 10:00:32
        13.12.2014      13-12-2014 10:00:32
        13.12.2014      13-12-2014 10:00:32

Upvotes: 0

Views: 165

Answers (1)

Ed Morton
Ed Morton

Reputation: 203209

awk scripts are a series of:

<condition> { <action> }

statements. Your code:

$2=substr($2,1,11)
gsub(/-/,".",$2)

is 2 conditions invoking the default action when true, equivalent to:

$2=substr($2,1,11) { print $0 }
gsub(/-/,".",$2) { print $0 }

You probably mean to write:

{
    $2=substr($2,1,11)
    gsub(/-/,".",$2)
}

so they're within an action part rather than a condition part of the script.

Upvotes: 2

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