one liner - open file and read

baxy77bax has asked for the wisdom of the Perl Monks concerning the following question:

hi,

well this maybe redundant but i'm curious. is there a way to do this from a command line:

open (IN, "<", $ARGV[0]);
my $i =0;
while (<IN>){$i++}
print $i;
[download]

so what i'm aiming for is the result of this :


perl -e 'open(IN,"<", $ARGV[0]);$i=0;while(<IN>){$i++};print $i' in.fi
+le
[download]

but without open(IN,"<", $ARGV[0]); and while. i would like just to say what want and that iteration is assumed so :

perl -ne '$i++; print $i' in.file
[download]

so the question is how to preserve the $i in


perl -ne '$i++; print $i' in.file
[download]

and print it when iterator reaches the end of the file

something like in awk but in all mighty Perl way !!!!

thnx

baxy

Comment on one liner - open file and read Select or Download Code

Replies are listed 'Best First'.
Re: one liner - open file and read by Corion (Patriarch) on Oct 07, 2010 at 17:28 UTC
See perlrun about the `-n` and `-p` switches: `perl -wnle "$i++;END{print $i}" in.fi` [download] ... or `perl -wnle "END{print $.}" in.fi` [download] ... or just `wc -l in.fi`.	[reply] [d/l] [select]
Re: one liner - open file and read by jwkrahn (Abbot) on Oct 07, 2010 at 17:55 UTC
`perl -lne '}{print $.' in.file` [download]	[reply] [d/l]
Re^2: one liner - open file and read by NetWallah (Canon) on Oct 07, 2010 at 18:07 UTC
That works, but I don't understand the syntax, or why it works. Please enlighten. -- Thanks. Syntactic sugar causes cancer of the semicolon. --Alan Perlis	[reply]
Re^3: one liner - open file and read by FunkyMonk (Bishop) on Oct 07, 2010 at 18:23 UTC
perlrun says of -n: causes Perl to assume the following loop around your program, which makes it iterate over filename arguments somewhat like sed -n or awk: `LINE: while (<>) { ... # your program goes here }` [download] So, perl replaces '`...`' with jwkrahn's '`}{print $.`'. Make sense now?	[reply] [d/l] [select]
Re^4: one liner - open file and read by NetWallah (Canon) on Oct 07, 2010 at 19:35 UTC
Re^3: one liner - open file and read by eyepopslikeamosquito (Archbishop) on Oct 07, 2010 at 20:09 UTC
The `}{` is known as the eskimo greeting, one of Perl's many secret operators.	[reply] [d/l]
Re: one liner - open file and read by JavaFan (Canon) on Oct 07, 2010 at 18:24 UTC
`$ wc -l < in.file` [download]	[reply] [d/l]
Re^2: one liner - open file and read by TomDLux (Vicar) on Oct 07, 2010 at 20:26 UTC
Don't re-direct; `wc` accepts a filename argument, or a list of filenames. `wc -l in.file # also check out when multiple files match the pattern ... wc .dat` [download] As Occam said: Entia non sunt multiplicanda praeter necessitatem.*	[reply] [d/l] [select]
Re^3: one liner - open file and read by JavaFan (Canon) on Oct 07, 2010 at 20:52 UTC
I know what wc is capable of. Hence the redirect. Run it with and without the redirect, and compare it to the output of the OP.	[reply]
Re^4: one liner - open file and read by ChuckularOne (Prior) on Oct 27, 2010 at 17:57 UTC