I've this error:
Use of uninitialized value in concatenation (.) or string at...
This is my code:
$queryH= $dbh->prepare($query);
$queryH->execute();
my $i=0;
my $result;
while (#data = $queryH->fetchrow_array())
{
$result=$data[$i];
if ($result)
{
print "$result \n";
}
else
{
print "Records Not Found!\n";
last;
}
print "\n";
$i++;
}
print "\n\n";
$queryH->finish();
$dbh->disconnect();
What error is there in my code?
The error is on the line:
$result=$data[$i];
You are starting out with $i=0 and you increment it with each pass of the while loop. You look at $data[$i] once for each line of database result. So for the first row, you look at $data[0]. For the second row of data, you look at $data[1] and so on. At some point, your $i (which is effectively a rowcount starting at zero) will be higher than the number of fields per row. That produces the error message.
If you put in a print "$i\n" in the beginning of the while block you will see what I am talking about.
Related
I am recieving a syntax error on "else" for this shell:
{for (i=8;i<=NF;i+=3)
{if ($0~"=>") # if-else statement designed to flag file / directory transfers
print "=> flag,"$1"," $2","$3","$4 ","$5","$6","$7"," $(i)","$(i+1)","$(i+2);
{split ($(i+2), array, "/");
for (x in array)
{j++;
a[j] =j;
printf (array[x] ",");}
printf ("%s\n", "");}
else
print "no => flag,"$1"," $2","$3","$4 ","$5","$6","$7"," $(i)","$(i+1)","$(i+2)
}
}
Can't figure out why. If I delete the array block (starting with split()), all is well. But I need to scan the contents of $(i+2), so cutting it does me no good.
Also, if anyone has guidance on a good list of how to interpret error messages, that would be great.
Thanks for your advice.
EDIT: here is the above script laid out with sensible formatting:
{
for (i=8;i<=NF;i+=3) {
if ($0~"=>") # if-else statement designed to flag file / directory transfers
print "=> flag,"$1"," $2","$3","$4 ","$5","$6","$7"," $(i)","$(i+1)","$(i+2);
{
split ($(i+2), array, "/");
for (x in array) {
j++;
a[j] =j;
printf (array[x] ",");
}
printf ("%s\n", "");
}
else
print "no => flag,"$1"," $2","$3","$4 ","$5","$6","$7"," $(i)","$(i+1)","$(i+2)
}
}
First thing first, since you didn't post any samples of input and expected output so didn't test it at all. Could you please try following, I hope you are running this in .awk script style. Also these are mostly syntax/cosmetic changes NOT on logic part, since no background was given on problem.
BEGIN{
OFS=","
}
{
for (i=8;i<=NF;i+=3){
if ($0~/=>/){
print "=> flag,"$1,$2,$3,$4,$5,$6,$7,$(i),$(i+1),$(i+2)
split ($(i+2), array, "/");
for(x in array){
j++;
a[j] =j;
printf (array[x] ",")
}
printf ("%s\n", "")
}
else{
print "no => flag",$1,$2,$3,$4,$5,$6,$7,$(i),$(i+1),$(i+2)
}
}
}
Problems fixed in OP's attempt:
{ starting curly braces(which indicates that if condition of for loop with multiple statements is started) could be in last of the line where they are present, NOT in next line, for better visibility purposes, I fixed in for loop and if condition first.
Since you are using regexp matching with a pattern so I fixed from $0~"=>" TO $0~/=>/.
Added BEGIN section in your attempt where I have set OFS(output field separator) value to , so that you need NOT to print like "," to print comma between variables, just , between variables will do the trick.
Fixed indentation, so that we are NOT confused where to close loop/condition and where to NOT.
I have this simple awk script with which I attempt to check the amount of characters in the first line.
if the first line has more of less than 10 characters I want to store the amount
of caracters into a var.
Somehow the first print statement works but storing that result into a var doesn't.
Please help.
I tried removing dollar sign " thelength=(length($0))"
and removing the parenthesis "thelength=length($0)" but it doen't print anything...
Thanks!
#!/bin/ksh
awk ' BEGIN {FS=";"}
{
if (NR==1)
if(length($0)!=10)
{
print(length($0))
thelength=$(length($0))
print "The length of the first line is: ",$thelength;
exit 1;
}
}
END { print "STOP" }' $1
Two issues dealing with mixing ksh and awk scripting ...
no need to make a sub-shell call within awk to obtain the length; use thelength=length($0)
awk variables do not require a leading $ when being referenced; use print ... ,thelength
So your code becomes:
#!/bin/ksh
awk ' BEGIN {FS=";"}
{
if (NR==1)
if(length($0)!=10)
{
print(length($0))
thelength=length($0)
print "The length of the first line is: ",thelength;
exit 1;
}
}
END { print "STOP" }' $1
I am struggling with resetting some awk variables. I have multiple lines of the form:
one two three ... ten
with various appearances of each word in every line. I am trying to count the number of times each word is one each line, separate from the counts from the other lines.
this is what I have so far:
{ for(i=length(Num); i>0; i--)
if( Num[i] == "one" )
{
oneCount++
}
else if( Num[i] == "two" )
{
twoCount++
}
else if( Num[i] == "three" )
{
threeCount++
}
...
}
when I print out the count values, the count doesn't reinitialize with each new line. how do i fix this?
any help is much appreciated
You seem very confused. To get a count of each field in a ;-separated line would be:
awk -F';' '{
split("",cnt) # or "delete cnt" if using GNU awk.
for (i=1;i<=NF;i++) {
cnt[$i]++
}
for (word in cnt) {
print word, cnt[word]
}
}' file
Now is there anything else you need it to do?
Try initializing an array in the BEGIN portion to however many variables you'd like to count. You can run a loop in the portion to clear the array at the beginning of every new line.
Alternatively, you could just reset the value of each variable to 0 or null in the portion of the program that executes every line, but I'm guessing you have many variables.
I've this error:
Use of uninitialized value $index in concatenation (.) or string at getdesc.pl line 43, <OctetsIn> line 2.
part of my code as follows:
my $select_sth = $dbh->prepare("SELECT Hid,Hostname,IP FROM Devices")
or die "$dbh->errstr";
$select_sth->execute() or die "$dbh->errstr";
while ( my $row_ref = $select_sth->fetchrow_hashref ) {
my $hostname = $row_ref->{'Hostname'};
if ( $hostname ne 'null' ) {
my $hid = $row_ref->{'Hid'};
my $ip = $row_ref->{'IP'};
my $desc = "null";
my $index = 0;
open( OctetsIn, "snmpwalk -v2c -c public $ip 1.3.6.1.2.1.18 |" )
or die "can't exec: $!";
while (<OctetsIn>) {
chomp;
print <OctetsIn> . "\n";
/IF-MIB::ifAlias.(\S+) = STRING: (\S+)/;
$index = $1;
$desc = $2;
$dbh->do(
"INSERT INTO Description (Hid,index,desc) Values ($hid,$index,'$desc')"
) or die "$dbh->errstr";
}
}
}
close(OctetsIn);
What error is there in my code? anyone knows how to fix the error ?
The error is on the line:
$dbh->do("INSERT INTO Description (Hid,index,desc) Values ($hid,$index,'$desc')") or die "$dbh->errstr";
You should test if regex was successful prior to assigning $1 to $index, ie.
# skip to next line if current did not match, as $1 and $2 are undefined
/IF-MIB::ifAlias.(\S+) = STRING: (\S+)/ or next;
There are three issues regarding your innermost while loop:
You're reading from the filehandle twice when trying to just print the current line:
while (<OctetsIn>) {
chomp;
print <OctetsIn> . "\n"; # Should be: print "$_\n";
Always verify that your regular expression matched before using capture variables.
/IF-MIB::ifAlias.(\S+) = STRING: (\S+)/;
$index = $1; # Will be undefined if regex doesn't match
$desc = $2;
Use placeholders and bind values instead of manually including values in a SQL statement:
Should aim to never interpolate values directly into a SQL statement like below:
"INSERT INTO Description (Hid,index,desc) Values ($hid,$index,'$desc')"
To clean up these three issues, I'd transform your inner while loop to something like the following.
while (<OctetsIn>) {
chomp;
print "$_\n";
if (my ($index, $desc) = /IF-MIB::ifAlias.(\S+) = STRING: (\S+)/) {
$dbh->do(
"INSERT INTO Description (Hid,index,desc) Values (?,?,?)",
undef, $hid, $index, $desc
) or die $dbh->errstr;
}
}
$index = $1;
your regexp doesn't match, so $1 is undef
the script was working. I added some comments and renamed it then submitted it. today my instructor told me it doesnt work and give me the error of awk 1 unexpected character '.'
the script is supposed to read a name in command line and return the student information for the name back.
right now I checked it and surprisingly it gives me the error.
I should run it by the command like this:
scriptName -v name="aname" -f filename
what is this problem and which part of my code make it?
#!/usr/bin/awk
BEGIN{
tmp=name;
nameIsValid;
if (name && tolower(name) eq ~/^[a-z]+$/ )
{
inputName=tolower(name)
nameIsValid++;
}
else
{
print "you have not entered the student name"
printf "Enter the student's name: "
getline inputName < "-"
tmp=inputName;
if (tolower(inputName) eq ~/^[a-z]+$/)
{
tmpName=inputName
nameIsValid++
}
else
{
print "Enter a valid name!"
exit
}
}
inputName=tolower(inputName)
FS=":"
}
{
if($1=="Student Number")
{
split ($0,header,FS)
}
if ($1 ~/^[0-9]+$/ && length($1)==8)
{
split($2,names," ")
if (tolower(names[1]) == inputName || tolower(names[2])==inputName )
{
counter++
for (i=1;i<=NF;i++)
{
printf"%s:%s ",header[i], $i
}
printf "\n"
}
}
}
END{
if (counter == 0 && nameIsValid)
{
printf "There is no record for the %-10s\n" , tmp
}
}
Here are the steps to fix the script:
Get rid of all those spurious NULL statements (trailing semi-colons at the end of lines).
Get rid of the unset variable eq (it is NOT an equality operator!) from all of your comparions.
Cleanup the indenting.
Get rid of that first non-functional nameIsValid; statement.
Change printf "\n" to the simpler print "".
Get rid of the useless ,FS arg to split().
Change name && tolower(name) ~ /^[a-z]+$/ to just the second part of that condition since if that matches then of course name is populated.
Get rid of all of those tolower()s and use character classes instead of explicit a-z ranges.
Get rid of the tmp variable.
Simplify your BEGIN logic.
Get rid of the unnecessary nameIsValid variable completely.
Make the awk body a bit more awk-like
And here's the result (untested since no sample input/output posted):
BEGIN {
if (name !~ /^[[:alpha:]]+$/ ) {
print "you have not entered the student name"
printf "Enter the student's name: "
getline name < "-"
}
if (name ~ /^[[:alpha:]]+$/) {
inputName=tolower(name)
FS=":"
}
else {
print "Enter a valid name!"
exit
}
}
$1=="Student Number" { split ($0,header) }
$1 ~ /^[[:digit:]]+$/ && length($1)==8 {
split(tolower($2),names," ")
if (names[1]==inputName || names[2]==inputName ) {
counter++
for (i=1;i<=NF;i++) {
printf "%s:%s ",header[i], $i
}
print ""
}
}
}
END {
if (counter == 0 && inputName) {
printf "There is no record for the %-10s\n" , name
}
}
I changed the shebang line to:
#!/usr/bin/awk -f
and then in command line didnt use -f. It is working now
Run the script in the following way:
awk -f script_name.awk input_file.txt
This seems to suppress the warnings and errors.
In my case, the problem was resetting the IFS variable to be IFS="," as suggested in this answer for splitting string into an array. So I resetted the IFS variable and got my code to work.
IFS=', '
read -r -a array <<< "$string"
IFS=' ' # reset IFS