Perl Language File I/O (reading and writing files)
Parameters
| Mode | Explaination |
|---|---|
> | Write (trunc). Will overwrite existing files. Creates a new file if no file was found |
>> | Write (append). Will not overwrite files but append new content at the end of it. Will also create a file if used for opening a non existing file. |
< | Read. Opens the file in read only mode. |
+< | Read / Write. Will not create or truncate the file. |
+> | Read / Write (trunc). Will create and truncate the file. |
+>> | Read / Write (append). Will create but not truncate the file. |
Remarks
chomp is often used when reading from a file. By default it trims the newline character, although for its full functionality refer to the perldocs.
Beware of the difference between characters and bytes: Not all encodings - especially UTF-8 - use 1-byte-characters. While this is handled pretty much flawlessly by PerlIO, there is one potential pitfall of note:
readuses characters for its length and offset parametersseekandtellalways use bytes for positioning
So don't use arithmetics based on these mixed values. Instead use e.g. Encode::encode('utf8',$value_by_read) to get the octets(bytes) from a readresult, whose count you can then use with tell and seek.
