I am searching for "o" then prints all lines with "o". Any suggestion/code I must apply?
data.txt:
j,o,b:
a,b,d:
o,l,e:
f,a,r:
e,x,o:
desired output:
j,o,b:
o,l,e:
e,x,o:
grep o data.txt
perl -ne 'print if (/o/);' <data.txt
If you have grep on your system, then grep o data.txt from the command line should do the trick.
Failing that, you could try Perl:
open IN, 'data.txt';
my #l = <IN>;
close IN;
foreach my $l (#l) {
$l =~ /o/ and print $l;
}
grep "o" data.txt
Does that help? I don't know Perl, but you can get the same output using the above grep.
print if /o/;
In Perl:
while (<>) { print if /o/; }
or with grep:
grep 'o' data.txt
as a very short one-liner:
> perl -pe'$_ x=/o/' filename
Related
I have a list of PCs and I need to append quotes and commas to each of them so that I can do a SQL query
List example
Row1|PCName|PC1.local
Row2|PCName|PC2.local
Row3|PCName|PC3.local
and I need to get this
"PC1.local", "PC2.local", "PC3.local", ......
Here is what I tried
cat list.txt | awk -F\| '{print $NF}' | perl -e 'while(<>){ print "\"$_\", ";}'
I get this
", "PC1.local
", "PC2.local
", "PC3.local
", "
How can I make those PCs show up in a single line and with the format that I need?
I know using awk or perl might be overkill for this and it could be done using Perl alone or awk alone, but I'm interested in learning how to pipe things to Perl. How can I make Perl print those PC names in the format I need?
How about:
#!/usr/bin/env perl
use strict;
use warnings;
print join ",", map { chomp; '"'.(split /\|/)[2].'"' } <DATA> ;
__DATA__
Row1|PCName|PC1.local
Row2|PCName|PC2.local
Row3|PCName|PC3.local
Output:
"PC1.local","PC2.local","PC3.local"
As a one liner:
perl -e 'print join ",", map { s/\n//; q{"}.(split /\|/)[2].q{"} } <>'
$ awk -F'|' '{printf "%s\"%s\"", (NR>1?", ":""), $3} END{print ""}' file
"PC1.local", "PC2.local", "PC3.local"
with unix toolset
$ cut -d'|' -f3 file | sed 's/.*/"&"/' | paste -s -d,
extract third field, wrap with quotes, join with comma
Here's a Perl one-line solution
$ perl -le 'print join ", ", map { /([^|\s]+)$/ && qq{"$1"} } <>' myfile
output
"PC1.local", "PC2.local", "PC3.local"
#!perl
use strict;
use warnings;
while ( my $line = readline(*STDIN) ) {
chomp $line;
my #machines = split /\|/, $line;
print join(',', map { '"' . $_ . '"' } #machines), "\n";
}
Output:
$ cat list.txt | perl test.pl
"Row1","PCName","PC1.local"
"Row2","PCName","PC2.local"
"Row3","PCName","PC3.local"
How to add a blank line after every grep result?
For example, grep -o "xyz" may give something like -
file1:xyz
file2:xyz
file2:xyz2
file3:xyz
I want the output to be like this -
file1:xyz
file2:xyz
file2:xyz2
file3:xyz
I would like to do something like
grep "xyz" | perl (code to add a new line after every grep result)
This is the direct answer to your question:
grep 'xyz' | perl -pe 's/$/\n/'
But this is better:
perl -ne 'print "$_\n" if /xyz/'
EDIT
Ok, after your edit, you want (almost) this:
grep 'xyz' * | perl -pe 'print "\n" if /^([^:]+):/ && ! $seen{$1}++'
If you don’t like the blank line at the beginning, make it:
grep 'xyz' * | perl -pe 'print "\n" if /^([^:]+):/ && ! $seen{$1}++ && $. > 1'
NOTE: This won’t work right on filenames with colons in them. :)½
If you want to use perl, you could do something like
grep "xyz" | perl -p -e 's/(.*)/\1\n/g'
If you want to use sed (where I seem to have gotten better results), you could do something like
grep "xyz" | sed 's/.*/\0\n/g'
This prints a newline after every single line of grep output:
grep "xyz" | perl -pe 'print "\n"'
This prints a newline in between results from different files. (Answering the question as I read it.)
grep 'xyx' * | perl -pe '/(.*?):/; if ($f ne $1) {print "\n"; $f=$1}'
Use a state machine to determine when to print a blank line:
#!/usr/bin/env perl
use strict;
use warnings;
# state variable to determine when to print a blank line
my $prev_file = '';
# change DATA to the appropriate input file handle
while( my $line = <DATA> ){
# did the state change?
if( my ( $file ) = $line =~ m{ \A ([^:]*) \: .*? xyz }msx ){
# blank lines between states
print "\n" if $file ne $prev_file && length $prev_file;
# set the new state
$prev_file = $file;
}
# print every line
print $line;
}
__DATA__
file1:xyz
file2:xyz
file2:xyz2
file3:xyz
Is there a simple way to mimic the effect of the -l command-line switch within perl scripts? (Of course, I can always chomp each line and then append "\n" to each line I print, but the point is to avoid having to do this.)
No. You can get the automatic appending of "\n" by using $\, but you have to add the chomp yourself.
Here's how -l works.
$ perl -MO=Deparse -ne 'print $_'
LINE: while (defined($_ = <ARGV>)) {
print $_;
}
$ perl -MO=Deparse -lne 'print $_'
BEGIN { $/ = "\n"; $\ = "\n"; } # -l added this line
LINE: while (defined($_ = <ARGV>)) {
chomp $_; # -l added this line
print $_;
}
(The comments are mine.) Notice that -l added a literal chomp $_ at the beginning of the loop generated by -n (and it only does that if you use -n or -p). There's no variable you can set to mimic that behaviour.
It's a little-known fact that -l, -n, and -p work by wrapping boilerplate text around the code you supply before it's compiled.
Yes, try using this at the beginning of your script after the shebang and strictures:
$/ = $\ = "\n"; # setting the output/input record separator like OFS in awk
and use in the loop :
chomp;
print;
Or like this :
use strict; use warnings;
use English qw/-no_match_vars/;
$OUTPUT_RECORD_SEPARATOR = "\n";
while (<>) {
chomp;
print;
}
I do not recommend to use
#!/usr/bin/perl -l
for a better clarity =)
See perldoc perlvar
You can add it to your shebang line:
#!/usr/bin/perl -l
I'm looking for a simple/elegant way to grep a file such that every returned line must match every line of a pattern file.
With input file
acb
bc
ca
bac
And pattern file
a
b
c
The command should return
acb
bac
I tried to do this with grep -f but that returns if it matches a single pattern in the file (and not all). I also tried something with a recursive call to perl -ne (foreach line of the pattern file, call perl -ne on the search file and try to grep in place) but I couldn't get the syntax parser to accept a call to perl from perl, so not sure if that's possible.
I thought there's probably a more elegant way to do this, so I thought I'd check. Thanks!
===UPDATE===
Thanks for your answers so far, sorry if I wasn't clear but I was hoping for just a one-line result (creating a script for this seems too heavy, just wanted something quick). I've been thinking about it some more and I came up with this so far:
perl -n -e 'chomp($_); print " | grep $_ "' pattern | xargs echo "cat input"
which prints
cat input | grep a | grep b | grep c
This string is what I want to execute, I just need to somehow execute it now. I tried an additional pipe to eval
perl -n -e 'chomp($_); print " | grep $_ "' pattern | xargs echo "cat input" | eval
Though that gives the message:
xargs: echo: terminated by signal 13
I'm not sure what that means?
One way using perl:
Content of input:
acb
bc
ca
bac
Content of pattern:
a
b
c
Content of script.pl:
use warnings;
use strict;
## Check arguments.
die qq[Usage: perl $0 <input-file> <pattern-file>\n] unless #ARGV == 2;
## Open files.
open my $pattern_fh, qq[<], pop #ARGV or die qq[ERROR: Cannot open pattern file: $!\n];
open my $input_fh, qq[<], pop #ARGV or die qq[ERROR: Cannot open input file: $!\n];
## Variable to save the regular expression.
my $str;
## Read patterns to match, and create a regex, with each string in a positive
## look-ahead.
while ( <$pattern_fh> ) {
chomp;
$str .= qq[(?=.*$_)];
}
my $regex = qr/$str/;
## Read each line of data and test if the regex matches.
while ( <$input_fh> ) {
chomp;
printf qq[%s\n], $_ if m/$regex/o;
}
Run it like:
perl script.pl input pattern
With following output:
acb
bac
Using Perl, I suggest you read all the patterns into an array and compile them. Then you can read through your input file using grep to make sure all of the regexes match.
The code looks like this
use strict;
use warnings;
open my $ptn, '<', 'pattern.txt' or die $!;
my #patterns = map { chomp(my $re = $_); qr/$re/; } grep /\S/, <$ptn>;
open my $in, '<', 'input.txt' or die $!;
while (my $line = <$in>) {
print $line unless grep { $line !~ $_ } #patterns;
}
output
acb
bac
Another way is to read all the input lines and then start filtering by each pattern:
#!/usr/bin/perl
use strict;
use warnings;
open my $in, '<', 'input.txt' or die $!;
my #matches = <$in>;
close $in;
open my $ptn, '<', 'pattern.txt' or die $!;
for my $pattern (<$ptn>) {
chomp($pattern);
#matches = grep(/$pattern/, #matches);
}
close $ptn;
print #matches;
output
acb
bac
Not grep and not a one liner...
MFILE=file.txt
PFILE=patterns
i=0
while read line; do
let i++
pattern=$(head -$i $PFILE | tail -1)
if [[ $line =~ $pattern ]]; then
echo $line
fi
# (or use sed instead of bash regex:
# echo $line | sed -n "/$pattern/p"
done < $MFILE
A bash(Linux) based solution
#!/bin/sh
INPUTFILE=input.txt #Your input file
PATTERNFILE=patterns.txt # file with patterns
# replace new line with '|' using awk
PATTERN=`awk 'NR==1{x=$0;next}NF{x=x"|"$0}END{print x}' "$PATTERNFILE"`
PATTERNCOUNT=`wc -l <"$PATTERNFILE"`
# build regex of style :(a|b|c){3,}
PATTERN="($PATTERN){$PATTERNCOUNT,}"
egrep "${PATTERN}" "${INPUTFILE}"
Here's a grep-only solution:
#!/bin/sh
foo ()
{
FIRST=1
cat pattern.txt | while read line; do
if [ $FIRST -eq 1 ]; then
FIRST=0
echo -n "grep \"$line\""
else
echo -n "$STRING | grep \"$line\""
fi
done
}
STRING=`foo`
eval "cat input.txt | $STRING"
How can I write a Perl script to convert a text file to all upper case letters?
perl -ne "print uc" < input.txt
The -n wraps your command line script (which is supplied by -e) in a while loop. A uc returns the ALL-UPPERCASE version of the default variable $_, and what print does, well, you know it yourself. ;-)
The -p is just like -n, but it does a print in addition. Again, acting on the default variable $_.
To store that in a script file:
#!perl -n
print uc;
Call it like this:
perl uc.pl < in.txt > out.txt
$ perl -pe '$_= uc($_)' input.txt > output.txt
perl -pe '$_ = uc($_)' input.txt > output.txt
But then you don't even need Perl if you're using Linux (or *nix). Some other ways are:
awk:
awk '{ print toupper($0) }' input.txt >output.txt
tr:
tr '[:lower:]' '[:upper:]' < input.txt > output.txt
$ perl -Tpe " $_ = uc; " --
$ perl -MO=Deparse -Tpe " $_ = uc; " -- a s d f
LINE: while (defined($_ = <ARGV>)) {
$_ = uc $_;
}
continue {
die "-p destination: $!\n" unless print $_;
}
-e syntax OK
$ cat myprogram.pl
#!/usr/bin/perl -T --
LINE: while (defined($_ = <ARGV>)) {
$_ = uc $_;
}
continue {
die "-p destination: $!\n" unless print $_;
}