I want to replace word "a" to "red" in a.text files. I want to edit the same file so I tried this code but it does not work. Where am I going wrong?
#files=glob("a.txt");
foreach my $file (#files)
{
open(IN,$file) or die $!;
<IN>;
while(<IN>)
{
$_=~s/a/red/g;
print IN $file;
}
close(IN)
}
I'd suggest it's probably easier to use perl in sed mode:
perl -i.bak -p -e 's/a/red/g' *.txt
-i is inplace edit (-i.bak saves the old as .bak - -i without a specifier doesn't create a backup - this is often not a good idea).
-p creates a loop that iterates all the files specified one line at a time ($_), applying whatever code is specified by -e before printing that line. In this case - s/// applies a sed-style patttern replacement to $_, so this runs a search and replace over every .txt file.
Perl uses <ARVG> or <> to do some magic - it checks if you specify files on your command line - if you do, it opens them and iterates them. If you don't, it reads from STDIN.
So you can also do:
somecommand.sh | perl -i.bak -p -e 's/a/red/g'
In your code you are using same filehandle to write which you have used for open the file to reading. Open the same file for write mode and then write.
Always use lexical filehandle and three arguments to open a file. Here is your modified code:
use warnings;
use strict;
my #files = glob("a.txt");
my #data;
foreach my $file (#files)
{
open my $fhin, "<", $file or die $!;
<$fhin>;
while(<$fhin>)
{
$_ =~ s/\ba\b/red/g;
push #data, $_;
}
open my $fhw, ">", $file or die "Couldn't modify file: $!";
print $fhw #data;
close $fhw;
}
Here is another way (read whole file in a scalar):
foreach my $file (glob "/path/to/dir/a.txt")
{
#read whole file in a scalar
my $data = do {
local $/ = undef;
open my $fh, "<", $file or die $!;
<$fh>;
};
$data =~ s/\ba\b/red/g; #replace a with red,
#modify the file
open my $fhw, ">", $file or die "Couldn't modify file: $!";
print $fhw $data;
close $fhw;
}
Related
This is my script count.pl, I am trying to count the number of lines in a file.
The script's code :
chdir $filepath;
if (-e "$filepath"){
$total = `wc -l < file.list`;
printf "there are $total number of lines in file.list";
}
i can get a correct output, but i do not want to count blank lines and anything in the file that start with #. any idea ?
As this is a Perl program already open the file and read it, filtering out lines that don't count with
open my $fh, '<', $filename or die "Can't open $filename: $!";
my $num_lines = grep { not /^$|^\s*#/ } <$fh>;
where $filename is "file.list." If by "blank lines" you mean also lines with spaces only then chagne regex to /^\s*$|^\s*#/. See grep, and perlretut for regex used in its condition.
That filehandle $fh gets closed when the control exits the current scope, or add close $fh; after the file isn't needed for processing any more. Or, wrap it in a block with do
my $num_lines = do {
open my $fh, '<', $filename or die "Can't open $filename: $!";
grep { not /^$|^\s*#/ } <$fh>;
};
This makes sense doing if the sole purpose of opening that file is counting lines.
Another thing though: an operation like chdir should always be checked, and then there is no need for the race-sensitive if (-e $filepath) either. Altogether
# Perhaps save the old cwd first so to be able to return to it later
#my $old_cwd = Cwd::cwd;
chdir $filepath or die "Can't chdir to $filepath: $!";
open my $fh, '<', $filename or die "Can't open $filename: $!";
my $num_lines = grep { not /^$|^\s*#/ } <$fh>;
A couple of other notes:
There is no reason for printf. For all normal prints use say, for which you need use feature qw(say); at the beginning of the program. See feature pragma
Just in case, allow me to add: every program must have at the beginning
use warnings;
use strict;
Perhaps the original intent of the code in the question is to allow a program to try a non-existing location, and not die? In any case, one way to keep the -e test, as asked for
#my $old_cwd = Cwd::cwd;
chdir $filepath or warn "Can't chdir to $filepath: $!";
my $num_lines;
if (-e $filepath) {
open my $fh, '<', $filename or die "Can't open $filename: $!";
$num_lines = grep { not /^$|^\s*#/ } <$fh>;
}
where I still added a warning if chdir fails. Remove that if you really don't want it. I also added a declaration of the variable that is assigned the number of lines, with my $total_lines;. If it is declared earlier in your real code then of course remove that line here.
perl -ne '$n++ unless /^$|^#/ or eof; print "$n\n" if eof'
Works with multiple files too.
perl -ne '$n++ unless /^$|^#/ or eof; END {print "$n\n"}'
Better for a single file.
open(my $fh, '<', $filename);
my $n = 0;
for(<$fh>) { $n++ unless /^$|^#/}
print $n;
Using sed to filter out the "unwanted" lines in a single file:
sed '/^\s*#/d;/^\s*$/d' infile | wc -l
Obviously, you can also replace infile with a list of files.
The solution is very simple, no any magic.
use strict;
use warnings;
use feature 'say';
my $count = 0;
while( <> ) {
$count++ unless /^\s*$|^\s*#/;
}
say "Total $count lines";
Reference:
<>
I have list of files as below:
RF1.lib
RF2.lib
RF3.lib
etc..
In each of the *.lib files I have to replace this string vlib with the name of the file like RF1, RF2 etc.
I am using the sed command to search and replace the string as below:
sed -i -e 's/vlib/RF1/g' RF1.lib
sed -i -e 's/vlib/RF2/g' RF2.lib
But I am having to do this multiple times to search and replace for every file.
Is there a way I can open the files in a loop and use the sed command to do the replacement in each file?
Here is a Perl script which will replace the string in each file with filename:
#!/usr/bin/perl
use warnings;
use strict;
foreach my $file (glob "/path/to/dir/*.lib") #get all the '.lib' files from dir
{
my ($filename) = $file =~ m/([^\/]+)\.lib$/; #get the filename
open my $fh, "<", $file or die $!;
my #data = <$fh>;
close $fh;
foreach my $line (#data)
{
$line =~ s/\bvlib\b/$filename/g; #replace string with filename
}
#modify the file
open my $fhw, ">", $file or die "Couldn't modify file: $!";
print $fhw #data;
close $fhw;
}
Edit: As Borodin suggested in comment, reading whole file into scalar:
foreach my $file (glob "/path/to/dir/*.lib") #get all the '.lib' files from dir
{
my ($filename) = $file =~ m/([^\/]+)\.lib$/; #get the filename
#read whole file in a scalar
my $data = do {
local $/ = undef;
open my $fh, "<", $file or die $!;
<$fh>;
};
$data =~ s/\bvlib\b/$filename/g; #replace string with filename
#modify the file
open my $fhw, ">", $file or die "Couldn't modify file: $!";
print $fhw $data;
close $fhw;
}
Sure. You can say:
for f1 in RF*.lib: do
j=`basemame $f1 .lib`
sed -i -e "s/vlib/$j/g" $f1
done
This might work for you (GNU sed):
sed -r 's|(.*)\.*|sed -i "s/vlib/\1/g" &|e' fileOfFiles
This evaluates a sed command for each of the files in the file containing files. If you prefer the output of the command can be piped into a shell for the same effect, like so:
sed -r 's|(.*)\.*|sed -i "s/vlib/\1/g" &|' fileOfFiles | sh
My program is trying to search a string from multiple files in a directory. The code searches for single patterns like perl but fails to search a long string like Status Code 1.
Can you please let me know how to search for strings with multiple words?
#!/usr/bin/perl
my #list = `find /home/ad -type f -mtime -1`;
# printf("Lsit is $list[1]\n");
foreach (#list) {
# print("Now is : $_");
open(FILE, $_);
$_ = <FILE>;
close(FILE);
unless ($_ =~ /perl/) { # works, but fails to find string "Status Code 1"
print "found\n";
my $filename = 'report.txt';
open(my $fh, '>>', $filename) or die "Could not open file '$filename' $!";
say $fh "My first report generated by perl";
close $fh;
} # end unless
} # end For
There are a number of problems with your code
You must always use strict and use warnings at the top of every Perl program. There is little point in delcaring anything with my without strict in place
The lines returned by the find command will have a newline at the end which must be removed before Perl can find the files
You should use lexical file handles (my $fh instead of FILE) and the three-parameter form of open as you do with your output file
$_ = <FILE> reads only the first line of the file into $_
unless ($_ =~ /perl/) is inverted logic, and there's no need to specify $_ as it is the default. You should write if ( /perl/ )
You can't use say unless you have use feature 'say' at the top of your program (or use 5.010, which adds all features available in Perl v5.10)
It is also best to avoid using shell commands as Perl is more than able to do anything that you can using command line utilities. In this case -f $file is a test that returns true if the file is a plain file, and -M $file returns the (floating point) number of days since the file's modification time
This is how I would write your program
#!/usr/bin/perl
use strict;
use warnings;
use 5.010;
for my $file ( glob '/home/ad/*' ) {
next unless -f $file and int(-M $file) == 1;
open my $fh, '<', $file or die $!;
while ( <$fh> ) {
if ( /perl/ ) {
print "found\n";
my $filename = 'report.txt';
open my $out_fh, '>>', $filename or die "Could not open file '$filename': $!";
say $fh "My first report generated by perl";
close $out_fh;
last;
}
}
}
it should have matched unless $_ contains text in different case.
try this.
unless($_ =~ /Status\s+Code\s+1/i) {
Change
unless ($_ =~ /perl/) {
to:
unless ($_ =~ /(Status Code 1)/) {
I am certain the above works, except it's case sensitive.
Since you question it, I rewrote your script to make more sense of what you're trying to accomplish and implement the above suggestion. Correct me if I am wrong, but you're trying to make a script which matches "Status Code 1" in a bunch of files where last modified within 1 day and print the filename to a text file.
Anyways, below is what I recommend:
#!/usr/bin/perl
use strict;
use warnings;
my $output_file = 'report.txt';
my #list = `find /home/ad -type f -mtime -1`;
foreach my $filename (#list) {
print "PROCESSING: $filename";
open (INCOMING, "<$filename") || die "FATAL: Could not open '$filename' $!";
foreach my $line (<INCOMING>) {
if ($line =~ /(Status Code 1)/) {
open( FILE, ">>$output_file") or die "FATAL: Could not open '$output_file' $!";
print FILE sprintf ("%s\n", $filename);
close(FILE) || die "FATAL: Could not CLOSE '$output_file' $!";
# Bail when we get the first match
last;
}
}
close(INCOMING) || die "FATAL: Could not close '$filename' $!";
}
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 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