Break one liner command line script after first match

[saumitra121]

I have a file which have data like

this is some data
this is other data
this is new data

Now I want to check(using a regex) whether a pattern exist in file or not. If yes then print the matched text and exit. In case the pattern occurs more than once, then the one liner should break after first match.

Lets for example say that I want to check for pattern "data" in my file. I am using following one liner.

 perl -ne'/(data)/ && print $1' file.txt

The problem with this is that it is NOT exiting after first match and prints matched content thrice.

How can I modify this so that execution will stop after first match?

Please note that instead of "data" i can provide any regex. Also I can't use a script. This has to be a command line one liner in perl(no awk or grep). File size can be as big as 2 GB.

[McA]

Hi

why not just exiting after printing the matched line?

UPDATE: perl -ne'/(data)/ && print($1) && exit' file.txt

McA

[hdb]

Or die!

perl -ne'/(data)/ && die $1' file.txt

[2teez]

How can I modify this so that execution will stop after first match
You can do: perl -ne'/(data)/ && print $1 and last' file.txt

[McA]

Hi,

as you showed it with your solution: Be aware of the subtle difference between:

perl -ne'/(data)/ && print $1 and last' file.txt

perl -ne'/(data)/ && print $1 && last' file.txt

That may bite someone (by the way: I was bitten ;-) )

McA

[2teez]

Hi,
Be aware of the subtle difference between:

perl -ne'/(data)/ && print $1 and last' file.txt

perl -ne'/(data)/ && print $1 && last' file.txt

Of course, I saw the subtle difference, and how you used

.. print ($1) ...


the parentheses which is effectively the same thing if "and" is used instead of "&&"
check this:

Using


perl -MO=Deparse -ne'/(data)/ && print $1 && last' file.txt

you gets:

LINE: while (defined($_ = <ARGV>)) {
    print $1 && last if /(data)/;
}

but using


perl -MO=Deparse -ne'/(data)/ && print ($1) && last' file.txt

gives:

LINE: while (defined($_ = <ARGV>)) {
    last if /(data)/ and print $1;
}

Which is same as this:


perl -MO=Deparse -ne'/(data)/ && print $1 and last' file.txt

LINE: while (defined($_ = <ARGV>)) {
    last if /(data)/ and print $1;
}