I want to get the unique elements (lines) from a file which I will further send through email.
I have tried 2 methods but both are not working:
1st way:
my #array = "/tmp/myfile.$device";
my %seen = ();
my $file = grep { ! $seen{ $_ }++ } #array;
2nd way :
my $filename = "/tmp/myfile.$device";
cat $filename |sort | uniq > $file
How can I do it?
You seem to have forgotten to read the file!
open(my $fh, '<', $file_name)
or die("Can't open \"$file_name\": $!\n");
my %seen;
my #unique = grep !$seen{$_}++, <$fh>;
You need to open the file and read it.
"cat" is a shell command not perl
Try something like this
my $F;
die $! if(!open($F,"/tmp/myfile.$device"));
my #array = <$F>;
my %seen = (); my $file = grep { ! $seen{ $_ }++ } #array;
The die $! will stop the program with an error if the file doesn't open correctly;
#array=<$F> reads all the data from the file $F opened above into the array.
If you rig the argument list, you can make Perl open the file automatically, using:
perl -n -e 'BEGIN{#ARGV=("/tmp/myfile.device");} print if $count{$_}++ == 0;'
Related
could anyone please share with me a snippet where i can do a grep search in perl file. Example,
i need this grep: grep 1115852311 /opt/files/treated/postpaid/*
to be done in perl script and print all the matches
tried the below, but did not work :
my $start_dir= "\opt\files\treated\postpaid\";
my $file_name = "*";
my #filematches;
opendir(DIR, "$start_dir");
#xml_files = grep(1115852311,readdir(DIR));
print #xml_files;
A good start would be to read the documentation for grep(). If you do, you'll see that Perl's grep() works rather differently to the Unix grep command. The Unix command just looks for text in a list of files. The Perl version works on any list of data and returns any elements in that list for which an arbitrary Boolean expression is true.
A Perl version of the Unix command would look something like this:
while (<$some_open_filehandle>) {
print if /$some_string/;
}
That's not quite what you want, but we can use it as a start. First, let's write something that takes a filename and string and checks whether the string appears in the file:
sub is_string_in_file {
my ($filename, $string) = #_;
open my $fh, '<', $filename or die "Cannot open file '$filename': $!\n";
return grep { /$string/ } <$fh>;
}
We can now use that in a loop which uses readdir() to get a list of files.
my #files;
my $dir = '/opt/files/treated/postpaid/';
opendir my $dh, $dir or die $!;
while (my $file = readdir($dh)) {
if (is_string_in_file("$dir$file", 1115852311) {
push #files, "$dir$file";
}
}
After running that code, the list of files that contain your string will be in #files.
You might want to look at glob() instead of opendir() and readdir().
used the below snippet to achieve what i wanted
#!/usr/bin/perl
use strict;
use warnings;
sub is_string_in_file {
my ($filename, $string) = #_;
open my $fh, '<', $filename
or die "Cannot open file \n";
while(my $line = <$fh>){
if($line =~ /$string/){
print $string;
print $filename."\n";
}
}
#return grep { $_ eq $string } <$fh>;
}
my #files;
my $dir = '/opt/files/treated/postpaid/';
opendir my $dh, $dir or die $!;
while (my $file = readdir($dh)) {
is_string_in_file("$dir$file", 1115852311);
}
I have two text files and I want to read them by passing argument at command line.
Now how to take second file? When I give the second file name command line is not reading. Please suggest.
I have used $ARGV[0] and $ARGV[1] in the code to pass the arguments at command line.
$ ./read.pl file1 file2
Reading file1
Reading file2
$ cat read.pl
#!/usr/bin/perl
use strict;
use warnings;
readFile($_) for #ARGV;
sub readFile {
my $filename = shift;
print "Reading $filename\n";
#OPEN CLOSE stuff here
}
my ($file1, $file2) = #ARGV;
open my $fh1, '<', $file1 or die $!;
open my $fh2, '<', $file2 or die $!;
while (<$fh1>) {
do something with $_
}
while (<$fh2>) {
do something with $_
}
close $fh1;
close $fh2;
Where $_ is the default variable.
run as:
perl readingfile.pl filename1 filename2
I am trying to solve below issues.
I have 2 files. Address.txt and File.txt. I want to replace all A/B/C/D (File.txt) with corresponding string value (Read from Address.txt file) using perl script. It's not replacing in my output file. I am getting same content of File.txt.
I tried below codes.
Here is Address.txt file
A,APPLE
B,BAL
C,CAT
D,DOG
E,ELEPHANT
F,FROG
G,GOD
H,HORCE
Here is File.txt
A B C
X Y X
M N O
D E F
F G H
Here is my code :
use strict;
use warnings;
open (MYFILE, 'Address.txt');
foreach (<MYFILE>){
chomp;
my #data_new = split/,/sm;
open INPUTFILE, "<", $ARGV[0] or die $!;
open OUT, '>ariout.txt' or die $!;
my $src = $data_new[0];
my $des = $data_new[1];
while (<INPUTFILE>) {
# print "In while :$src \t$des\n";
$_ =~ s/$src/$des/g;
print OUT $_;
}
close INPUTFILE;
close OUT;
# /usr/bin/perl -p -i -e "s/A/APPLE/g" ARGV[0];
}
close (MYFILE);
If i Write $_ =~ s/A/Apple/g;
Then output file is fine and A is replacing with "Apple". But when dynamically coming it's not getting replaced.
Thanks in advance. I am new in perl scripting language . Correct me if I am wrong any where.
Update 1: I updated below code . It's working fine now. My questions Big O of this algo.
Code :
#!/usr/bin/perl
use warnings;
use strict;
open( my $out_fh, ">", "output.txt" ) || die "Can't open the output file for writing: $!";
open( my $address_fh, "<", "Address.txt" ) || die "Can't open the address file: $!";
my %lookup = map { chomp; split( /,/, $_, 2 ) } <$address_fh>;
open( my $file_fh, "<", "File1.txt" ) || die "Can't open the file.txt file: $!";
while (<$file_fh>) {
my #line = split;
for my $char ( #line ) {
( exists $lookup{$char} ) ? print $out_fh " $lookup{$char} " : print $out_fh " $char ";
}
print $out_fh "\n";
}
Not entirely sure how you want your output formatted. Do you want to keep the rows and columns as is?
I took a similar approach as above but kept the formatting the same as in your 'file.txt' file:
#!/usr/bin/perl
use warnings;
use strict;
open( my $out_fh, ">", "output.txt" ) || die "Can't open the output file for writing: $!";
open( my $address_fh, "<", "address.txt" ) || die "Can't open the address file: $!";
my %lookup = map { chomp; split( /,/, $_, 2 ) } <$address_fh>;
open( my $file_fh, "<", "file.txt" ) || die "Can't open the file.txt file: $!";
while (<$file_fh>) {
my #line = split;
for my $char ( #line ) {
( exists $lookup{$char} ) ? print $out_fh " $lookup{$char} " : print $out_fh " $char ";
}
print $out_fh "\n";
}
That will give you the output:
APPLE BAL CAT
X Y X
M N O
DOG ELEPHANT FROG
FROG GOD HORCE
Here's another option that lets Perl handle the opening and closing of files:
use strict;
use warnings;
my $addresses_txt = pop;
my %hash = map { $1 => $2 if /(.+?),(.+)/ } <>;
push #ARGV, $addresses_txt;
while (<>) {
my #array;
push #array, $hash{$_} // $_ for split;
print "#array\n";
}
Usage: perl File.txt Addresses.txt [>outFile.txt]
The last, optional parameter directs output to a file.
Output on your dataset:
APPLE BAL CAT
X Y X
M N O
DOG ELEPHANT FROG
FROG GOD HORCE
The name of the addresses' file is implicitly popped off of #ARGV for use later. Then, a hash is built, using the key/value pairs in File.txt.
The addresses' file is read, splitting each line into its single elements, and the defined-or (//) operator is used to returned the defined hash item or the single element, which is then pushed onto #array. Finally, the array is interpolated in a print statement.
Hope this helps!
First, here is your existing program, rewritten slightly
open the address file
convert the address file to a hash so that the letters are the keys and the strings the values
open the other file
read in the single line in it
split the line into single letters
use the letters to lookup in the hash
use strict;
use warnings;
open(my $a,"Address.txt")||die $!;
my %address=map {split(/,/) } map {split(' ')} <$a>;
open(my $f,"File.txt")||die $!;
my $list=<$f>;
for my $letter (split(' ',$list)) {
print $address{$letter}."\n" if (exists $address{$letter});
}
to make another file with the substitutions in place alter the loop that processes $list
for my $letter (split(' ',$list)) {
if (exists $address{$letter}) {
push #output, $address{$letter};
}
else {
push #output, $letter;
}
}
open(my $o,">newFile.txt")||die $!;
print $o "#output";
Your problem is that in every iteration of your foreach loop you overwrite any changes made earlier to output file.
My solution:
use strict;
use warnings;
open my $replacements, 'Address.txt' or die $!;
my %r;
foreach (<$replacements>) {
chomp;
my ($k, $v) = split/,/sm;
$r{$k} = $v;
}
my $re = '(' . join('|', keys %r) . ')';
open my $input, "<", $ARGV[0] or die $!;
while (<$input>) {
s/$re/$r{$1}/g;
print;
}
#!/usr/bin/perl -w
# to replace multiple text strings in a file with text from another file
#select text from 1st file, replace in 2nd file
$file1 = 'Address.txt'; $file2 = 'File.txt';
# save the strings by which to replace
%replacement = ();
open IN,"$file1" or die "cant open $file1\n";
while(<IN>)
{chomp $_;
#a = split ',',$_;
$replacement{$a[0]} = $a[1];}
close IN;
open OUT,">replaced_file";
open REPL,"$file2" or die "cant open $file2\n";
while(<REPL>)
{chomp $_;
#a = split ' ',$_; #replaced_data = ();
# replace strings wherever possible
foreach $i(#a)
{if(exists $replacement{$i}) {push #replaced_data,$replacement{$i};}
else {push #replaced_data,$i;}
}
print OUT trim(join " ",#replaced_data),"\n";
}
close REPL; close OUT;
########################################
sub trim
{
my $str = $_[0];
$str=~s/^\s*(.*)/$1/;
$str=~s/\s*$//;
return $str;
}
I have a file that looks like this:
I,like
blah...
I want to replace only the first line with 'i,am' to get:
i,am
blah...
These are big files, so this is what I did (based on this):
open(FH, "+< input.txt") or die "FAIL!";
my $header = <FH>;
chop($header);
$header =~ s/I,like/i,am/g;
seek FH, 0, 0; # go back to start of file
printf FH $header;
close FH;
However, I get this when I run it:
i,amke
blah...
I looks like the 'ke' from like is still there. How do I get rid of it?
What I would do is probably something like this:
perl -i -pe 'if ($. == 1) { s/.*/i,am/; }' yourfile.txt
Which will only affect the first line, when the line counter for the current file handle $. is equal to 1. The regex will replace everything except newline. If you need it to match your specific line, you can include that in the if-statement:
perl -i -pe 'if ($. == 1 and /^I,like$/) { s/.*/i,am/; }' yourfile.txt
You can also look into Tie::File, which allows you to treat the file like an array, which means you can simply do $line[0] = "i,am\n". It is mentioned that there may be performance issues with this module, however.
If the replacement has a different length than the original, you cannot use this technique. You can for example create a new file and then rename it to the original name.
open my $IN, '<', 'input.txt' or die $!;
open my $OUT, '>', 'input.new' or die $!;
my $header = <$IN>;
$header =~ s/I,like/i,am/g;
print $OUT $header;
print $OUT $_ while <$IN>; # Just copy the rest.
close $IN;
close $OUT or die $!;
rename 'input.new', 'input.txt' or die $!;
I'd just use Tie::File:
#! /usr/bin/env perl
use common::sense;
use Tie::File;
sub firstline {
tie my #f, 'Tie::File', shift or die $!;
$f[0] = shift;
untie #f;
}
firstline $0, '#! ' . qx(which perl);
Usage:
$ ./example
$ head -2 example
#! /bin/perl
use common::sense;
I want a Perl script to search in the mentioned directory and find those files
which contains the string ADMITTING DX and push those files to a new folder.
I am new to Perl and was trying this:
#!/usr/bin/perl
use strict;
use warnings;
use File::Find;
my $dir = '/usr/share/uci_cmc/uci_new_files/';
my $string = 'ADMITTING DX';
open my $results, '>', '/home/debarshi/Desktop/results.txt'
or die "Unable to open results file: $!";
find(\&printFile, $dir);
sub printFile {
return unless -f and /\.txt$/;
open my $fh, '<',, $_ or do {
warn qq(Unable to open "$File::Find::name" for reading: $!);
return;
};
while ($fh) {
if (/\Q$string/) {
print $results "$File::Find::name\n";
return;
}
}
}
You are reading the lines from the file as:
while ($fh)
which should be
while (<$fh>)
You can really do it with Perl and that's a great way. But there's no any complex text processing in your case so I'd just advise using bash one-liner:
for f in *.txt; do grep 'ADMITTING DX' $f >/dev/null && mv $f /path/to/destination/; done
And if you still need a Perl solution:
perl -e 'for my $f (glob "*.txt") { open F, $f or die $!; while(<F>){ if(/ADMITTING DX/){ rename $f, "/path/to/destination/$f" or die $!; last } close $f; }}'
There are two errors in your code. Firstly you have a superfluous comma in the open call in printFile. It should read
open my $fh, '<', $_ or do { ... };
and secondly you need a call to readline to fetch data from the opened file. You can do this with <$fh>, so the while loop should read
while (<$fh>) { ... }
Apart from that your code is fine