Pattern Matching and skipping

M

mattjones

Hi,

I've got a small problem....im searching for words in a sentence (from
a log file) then pulling the sentence and putting it in a database. My
problem is that if the word and thus the sentence is no in the log file
- it is missing the log file out altogether and now recording them in
the database.
Is there a way of telling the program to look for these words - and if
they are not there - just skip that pattern (leave the field blank) and
move to the next pattern?

<SNIP>

while (<LOG>) {
if (/FASTSEARCH|conflicting/) {
my @lines = split /\n/; {
foreach my $fast (@lines) {

while (<LOG>) {
if (/elapsed/) {
my @lines = split /\n/; {
foreach my $elapsed2 (@lines) {

So, the script looks for FASTSEARCH and conflicting......if these are
not present i'd like the script to leave the field blank and move to
the next pattern (elapsed).
At the moment my script works but a few of the log files don't contain
FASTSEARCH or conflicting and so are not getting read into the database
(presumably because i am just doing loop after loop and if it doesn't
pick up either of these words it breaks the chain!)

Thanks

Matt (PERL Newbie!)
 
M

Mumia W.

Hi,

I've got a small problem....im searching for words in a sentence (from
a log file) then pulling the sentence and putting it in a database. My
problem is that if the word and thus the sentence is no in the log file
- it is missing the log file out altogether and now recording them in
the database.
Is there a way of telling the program to look for these words - and if
they are not there - just skip that pattern (leave the field blank) and
move to the next pattern?

<SNIP>

while (<LOG>) {
if (/FASTSEARCH|conflicting/) {
my @lines = split /\n/; {
foreach my $fast (@lines) {

while (<LOG>) {
if (/elapsed/) {
my @lines = split /\n/; {
foreach my $elapsed2 (@lines) {

So, the script looks for FASTSEARCH and conflicting......if these are
not present i'd like the script to leave the field blank and move to
the next pattern (elapsed).
At the moment my script works but a few of the log files don't contain
FASTSEARCH or conflicting and so are not getting read into the database
(presumably because i am just doing loop after loop and if it doesn't
pick up either of these words it breaks the chain!)

Thanks

Matt (PERL Newbie!)
Click to expand...

Use the 'else' section of the if statement to tell perl what
to do when FASTSEARCH and conflicting are not there.

if (condition) {
... code ...
} else {
... code ...
}
 
M

mattjones

Use the 'else' section of the if statement to tell perl what
to do when FASTSEARCH and conflicting are not there.

if (condition) {
... code ...
} else {
... code ...
}
Click to expand...

ok thanks - i thought i had tried that today but ill give it another
shot tomorrow... perhaps i put the curly brackets in the wrong way!
 
M

mattjones

Ok, this hasn't seemed to work - either i am putting the } in the wrong
place (and i think i have tried most things)!

So i've tried:

while (<LOG>) {
if (/elapsed/) {
my @lines = split /\n/; {
foreach my $elapsed1 (@lines) {
{
while (<LOG>) {
if (/FASTSEARCH|conflicting/) {
} else {next } # this is where i
am having trouble
my @lines = split /\n/; {
foreach my $fast (@lines) {

while (<LOG>) {
if (/elapsed/) {
my @lines = split /\n/; {
foreach my $elapsed2 (@lines) {

So, i want the code to look for FASTSEARCH or conflicting and if they
aren't there - leave it blank but continue with the while loops.
 
A

anno4000

Ok, this hasn't seemed to work - either i am putting the } in the wrong
place (and i think i have tried most things)!

So i've tried:

while (<LOG>) {
if (/elapsed/) {
my @lines = split /\n/; {
Click to expand...

I haven't followed this thread, but the split() above is nonsense. If
you have read a line (with standard $/) the text contains at most one
line feed at he end. Splitting on linefeed doesn't do more than chomp.

Since it appears multiple times in your code, here and in your OP, I
thought I'd mention it.

Anno
 
M

MattJ83

while ( said:
I haven't followed this thread, but the split() above is nonsense. If
you have read a line (with standard $/) the text contains at most one
line feed at he end. Splitting on linefeed doesn't do more than chomp.

Since it appears multiple times in your code, here and in your OP, I
thought I'd mention it.

Anno
Click to expand...

When i remove split from my code however, the code doesn't work?!
 
M

MattJ83

Right - i thought it might be btter if i just paste all of the code i
have done:

#!/usr/central/bin/perl
use strict ;
#use warnings;
use DBI;

my @files= </home/USERNAME/logs/*.log>;
foreach my $file (@files) {

open (LOG,</home/USERNAME/logs/*.log>) or die "can't open LOG: $!\n";

while (<LOG>) {
if (/updates table/) {
my @lines = split /\n/; {
foreach my $info (@lines) {

while (<LOG>) {
if (/elapsed/) {
my @lines = split /\n/; {
foreach my $elapsed1 (@lines) {

while (<LOG>) {
if (/conflicting|FASTSEARCH/) {
my @lines = split /\n/; {
foreach my $fast (@lines) {

while (<LOG>) {
if (/elapsed/) {
my @lines = split /\n/; {
foreach my $elapsed2 (@lines) {

while (<LOG>) {
if (/inversions/) {
my @lines = split /\n/; {
foreach my $inversions (@lines) {

while (<LOG>) {
if (/elapsed/) {
my @lines = split /\n/; {
foreach my $elapsed3 (@lines) {

close(LOG) ;

my $dbh = DBI ->connect("dbi:Oracle:SERVER", "DATABASE", "PASSWORD")
or die "couldn't connect to database: $DBI::errstr\n";

$dbh->do("insert into LOGS values ('$file', '$info', '$elapsed1',
'$fast', '$elapsed2', '$inversions', '$elapsed3')") or die ("inse
rting data failure: $!\n");

$dbh->disconnect;
}}}}}}}}}}}}}}}}}}}}}}}}}
exit;

And all i want it to do is skip the line if it can't match the words
specified!!!
I just can't get the else or elseif statements to work...........

Sorry for the script - it isn't to brilliant but im new and it does
what i want it to do!!!
 
A

anno4000

MattJ83 said:
When i remove split from my code however, the code doesn't work?!
Click to expand...

Sure, just deleting the line will break it because the assignment to
@lines goes away too. The split() doesn't do anything useful, however.

With a little more context, your code is:

while (<LOG>) {
if (/elapsed/) {
my @lines = split /\n/; {
foreach my $elapsed1 (@lines) {
# ...

Change this to (untested):

while ( <LOG> ) {
chomp;
if ( /elapsed/ ) {
# ...

that is, drop both the line with split() and the next one "foreach ...".
The content of $_, which is what matters, will be the same in both
cases. The "foreach" loop would run only one time anyway.

Anno
 
D

David Squire

MattJ83 said:
Right - i thought it might be btter if i just paste all of the code i
have done:

#!/usr/central/bin/perl
use strict ;
#use warnings;
use DBI;

my @files= </home/USERNAME/logs/*.log>;
foreach my $file (@files) {

open (LOG,</home/USERNAME/logs/*.log>) or die "can't open LOG: $!\n";
Click to expand...

Surely you want to open each file in succession here. I don't know what
happens when you pass the result of a glob as the filename to open, but
I would bet that what you really wanted here was something like:

open (my $LOG, '<', $file) or die "can't open $file: $!\n";

(Note the use of a lexical file handle and the three argument form of
open. They're good habits to get into.)
while (<LOG>) {
Click to expand...

This gets a *single line* from the filehandle LOG and stores it
implicitly in $_
if (/updates table/) {
my @lines = split /\n/; {
Click to expand...

As has already been pointed out, you only have a single line to work
with here. You can't split into multiple lines on \n, since there is
only one \n, and the end of the line.

You need to change your logic to loop over the lines one by one.
foreach my $info (@lines) {

while (<LOG>) {
if (/elapsed/) {
my @lines = split /\n/; {
foreach my $elapsed1 (@lines) {

while (<LOG>) {
if (/conflicting|FASTSEARCH/) {
my @lines = split /\n/; {
foreach my $fast (@lines) {

while (<LOG>) {
if (/elapsed/) {
my @lines = split /\n/; {
foreach my $elapsed2 (@lines) {

while (<LOG>) {
if (/inversions/) {
my @lines = split /\n/; {
foreach my $inversions (@lines) {

while (<LOG>) {
if (/elapsed/) {
my @lines = split /\n/; {
foreach my $elapsed3 (@lines) {

close(LOG) ;
Click to expand...

[snip]

Indentation would help a lot too.


DS
 
A

anno4000

MattJ83 said:
When i remove split from my code however, the code doesn't work?!
Click to expand...

Sure, you threw out the baby with the bath water. The assignment to
@lines also goes away if you just delete the line.

The point is, @lines will only ever contain one element, the current
line minus its line feed. The same would be achieved by (untested)

while ( <LOG> ) {
chomp;
if ( /elapsed/ ) {
my @lines = ( $_);

I seem to remember that a loop over @lines follows. Both the variable
@lines and the loop can presumably go away too.

Anno
 
T

Tad McClellan

MattJ83 said:
Right - i thought it might be btter if i just paste all of the code i
have done:
Click to expand...


You should write your code so that its structure can be seen.

Each new block should increase the indent level.

while (<LOG>) {
if (/updates table/) {
my @lines = split /\n/; {
foreach my $info (@lines) {

while (<LOG>) {
if (/elapsed/) {
my @lines = split /\n/; {
foreach my $elapsed1 (@lines) {
Click to expand...


while (<LOG>) {
if (/updates table/) {
my @lines = split /\n/; { <== what is that "{" there for?
foreach my $info (@lines) {

while (<LOG>) {
if (/elapsed/) {
my @lines = split /\n/; {
foreach my $elapsed1 (@lines) {

Now it is easy to see that control can never get to /elapsed/
unless /updates table/ matches first.

Read the line once, test it many times.

while (<LOG>) {
if (/updates table/) {
# do stuff
}
elsif (/elapsed/) {
# do other stuff
}

I just can't get the else or elseif statements to work...........
Click to expand...


That is because you are not writing them correctly.
 
M

MattJ83

Sure, you threw out the baby with the bath water. The assignment to
@lines also goes away if you just delete the line.

The point is, @lines will only ever contain one element, the current
line minus its line feed. The same would be achieved by (untested)

while ( <LOG> ) {
chomp;
if ( /elapsed/ ) {
my @lines = ( $_);

I seem to remember that a loop over @lines follows. Both the variable
@lines and the loop can presumably go away too.

Anno
Click to expand...

By this do you mean i can replace that looping repetitious code by
using chomp; and ($_); ? Is ($_) just a short hand way of writing the
full variable or do u actually mean do this and then declare the $
variables somewhere else?
 
M

MattJ83

#!/usr/central/bin/perl
use strict ;
#use warnings;
use DBI;

my @files= </home/mmj19903/logs/*.log>;
foreach my $file (@files) {

open (LOG,</home/mmj19903/logs/*.log>) or die "can't open LOG: $!\n";

while (<LOG>) {
chomp;
if (/updates table/){
my @lines = ( $_); ;
foreach my $info (@lines) {

while (<LOG>) {
chomp;
if (/elapsed/) {
my @lines = ($_);
foreach my $elapsed1 (@lines) {

............
I presume this is what you mean't by the chomp - or did u mean
something more simple still?
So without the foreach line - i just get a global symbol $info (etc)
requires explicit package name....
 
D

David Squire

MattJ83 said:
#!/usr/central/bin/perl
use strict ;
#use warnings;
use DBI;

my @files= </home/mmj19903/logs/*.log>;
foreach my $file (@files) {

open (LOG,</home/mmj19903/logs/*.log>) or die "can't open LOG: $!\n";
Click to expand...

Read my earlier response about this line. You are not opening $file.


DS
 
M

MattJ83

David said:
Read my earlier response about this line. You are not opening $file.


DS
Click to expand...

I wasn't sure what you were gettign at with this line David - it works
for me - this code so far does what i want it to.....it opens the log
file puts the path of the log into a database field, and pulls out the
lines that have the soecific words in them and places these lines ina
database CLOB field. This is what i want - it repeats for each log in
the directory.....

Im a bit reluctant to change the code when this one works ok for me...
?
 
D

David Squire

MattJ83 said:
I wasn't sure what you were gettign at with this line David - it works
for me - this code so far does what i want it to.....it opens the log
file puts the path of the log into a database field, and pulls out the
lines that have the soecific words in them and places these lines ina
database CLOB field. This is what i want - it repeats for each log in
the directory.....

Im a bit reluctant to change the code when this one works ok for me...
Click to expand...

It will work so long as there is only one file that matches the pattern
in the glob </home/mmj19903/logs/*.log>. The lines above suggest that
you want to open each of the files in @files in turn. Your code does not
do that. You don't use the variable $file from the loop 'foreach my
$file (@files) {...}' anywhere. What is that loop for then?

DS
 
M

MattJ83

David said:
It will work so long as there is only one file that matches the pattern
in the glob </home/mmj19903/logs/*.log>. The lines above suggest that
you want to open each of the files in @files in turn. Your code does not
do that. You don't use the variable $file from the loop 'foreach my
$file (@files) {...}' anywhere. What is that loop for then?

DS
Click to expand...

As far as my limited PERL knowledge takes me (not far) i was under the
impression that that first few lines declares the directory then tells
it to loop the path name of the log file in the directory to the LOGID
column then open the log file and pull those lines (with /elapsed/ etc)
into the corresponding fields. This then repeats for the next log file
and then next.......it is only when the /pattern/ isn't matched that
the log file is not being recorded into the directory......

Thanks for your info...!!
 
D

David Squire

MattJ83 said:
As far as my limited PERL knowledge takes me (not far) i was under the
impression that that first few lines declares the directory then tells
it to loop the path name of the log file in the directory to the LOGID
column then open the log file and pull those lines (with /elapsed/ etc)
into the corresponding fields. ...
Click to expand...

[snip]

Here is an annotated version of those first few lines:
my @files= </home/USERNAME/logs/*.log>;
Click to expand...

Create an array called @files and initialise it with a list of all the
files or directories that match the pattern "/home/USERNAME/logs/*.log",
i.e. the same things you would see if you typed "ls
/home/USERNAME/logs/*.log" in your shell. This is called a glob.
foreach my $file (@files) {
Click to expand...

For each element of the array @files, create an alias for that element
called $file, and execute the code in the block that follows. You seem
not ever to use this - though if I were you I would.
open (LOG,</home/USERNAME/logs/*.log>) or die "can't open LOG: $!\n";
Click to expand...

Open a file handle LOG whose filename is given by the expression
"</home/USERNAME/logs/*.log>". This glob, identical to the one above, is
used here in scalar context, so what open gets is the next element of
the list in the glob... which means that you code actually does what you
want - to my surprise (I did not know about this behaviour of glob in a
scalar context)!

I still think it would be clearer to write:

my @filenames= </home/USERNAME/logs/*.log>;
foreach my $filename (@filenames) {
open my $LOG, '<', $filename or die "can't open $filename: $!\n";
.... # using $LOG wherever you had LOG
}

If you don't do that, your first two lines are redundant - there is
certainly no need to do the glob twice.


DS
 
A

anno4000

MattJ83 said:
By this do you mean i can replace that looping repetitious code by
using chomp; and ($_); ? Is ($_) just a short hand way of writing the
full variable or do u actually mean do this and then declare the $
variables somewhere else?
Click to expand...

Please use full pronouns.

No, I don't mean you should literally replace your code with mine.
All I'm saying is that my code does the same thing yours does but
without the spurious split.

You should reduce the code much more. I think another branch of
this thread is quite on the mark.

Anno
 
D

David Squire

David said:
If you don't do that, your first two lines are redundant - there is
certainly no need to do the glob twice.
Click to expand...

Ah. Not quite, since the loop means you call the second glob the right
number of times. Still, I think it is hard to understand - at least I
have shown that it was for me :)


DS
 

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