This short tutorial is to remember how to read a file from Perl. You should remember that it’s a two steps strategy:
- Open the file (that means connect to it)
- Read the file line-by-line (with a while loop)
This short tutorial is to remember how to read a file from Perl. You should remember that it’s a two steps strategy:
#!/usr/bin/perl # Get the filename from the user via command line $filename = $ARGV[0]; # Here we use the open command that reads a file (second parameter) # and link it to a "handle" (first parameters, conventionally uppercase). # "||" means "or", that is if open returns false... exit with an error message open(FILE, "$filename") || die " FATAL ERROR:\n Unable to open \"$file\".\n"; # Now we retrieve line by line calling the file handle with < and >. # Line content is stored in the special scalar "$_" while (<FILE>) { $linecounter++; print "$linecounter: $_"; } |
to use this script we need to add a parameter to the command line: the filename! eg:
perl script.pl filename.txt |
You can find a detailed tutorial on the open command here.