How do I grep a string in a file in perl?

How do I grep a string in a file in perl?

#!/usr/bin/perl -w open(FILE,”my_foo”); if (grep{/my_word/} ){ print “word found\n”; }else{ print “word not found\n”; } close FILE; remember, if your word in the file is My_word and not my_word it will not match.

How do I grep multiple strings in perl?

Grep Multiple Patterns To search for multiple patterns, use the OR (alternation) operator. The alternation operator | (pipe) allows you to specify different possible matches that can be literal strings or expression sets. This operator has the lowest precedence of all regular expression operators.

What does QW do in perl?

The qw operator in Perl is used to extract each element of the given string as it is in an array of elements in single-quote ( ‘ ‘ ). This function stands for quote word because it considers each word of the given string as it is quoted like qw(Geeks for Geeks) is equivalent to (‘Geeks’, ‘for’, ‘Geeks’).

How do I use awk in perl?

Aside from the fact that what are you trying to achieve by executing awk from within perl (since it could be accomplished using the latter itself), you could use the q operator: $cmd = q(awk -F”\t” ‘{if($1==”a” && $2==”b”) print $1,$2}’ file. txt | wc -l); $n = system($cmd);

How do I read a text file in Perl?

Perl Read File

  1. First, we used the open() function to open a file for reading.
  2. Second, the syntax while() is equivalent to while(defined($_ = ) . We read a line from a file and assigned it to the special variable $_ .
  3. Third, we displayed each line of the file by passing the variable $_ to the print function.

How do I combine two grep commands?

Two possibilities:

  1. Group them: { grep ‘substring1’ file1.txt grep ‘substring2’ file2.txt } > outfile.txt.
  2. Use the appending redirection operator >> for the second redirection: grep ‘substring1’ file1.txt > outfile.txt grep ‘substring2’ file2.txt >> outfile.txt.

How do I split a string in Perl?

Perl | split() Function. split() is a string function in Perl which is used to split or you can say to cut a string into smaller sections or pieces. There are different criteria to split a string, like on a single character, a regular expression(pattern), a group of characters or on undefined value etc..

How to write a grep function in Perl?

Perl grep Function 1 Description. This function extract any elements from LIST for which EXPR is TRUE. 2 Syntax 3 Return Value. This function returns the number of times the expression returned true in scalar context and list of elements that matched the expression in list context. 4 Example

Can a grep function filter a list of values?

That grep function can filter values from a list of values or an array based on any kind of condition. This article is not about the grep function. This article is about finding certain strings in a file, just as the command-line grep does.

How to use grep function in scalar context?

This function extract any elements from LIST for which EXPR is TRUE. Following is the simple syntax for this function − This function returns the number of times the expression returned true in scalar context and list of elements that matched the expression in list context. Following is the example code showing its basic usage −

When to use a regular expression in Perl?

In the above code, Regular expression /^d/ is used to get the integer value from the given array and discard the remaining elements. In the above code, Regular expression !/^R/ is used to get the elements not starting with ‘R’ and discard the elements which start with ‘R’.