https://www.tutorialspoint.com/perl

"# Perl"

Perl - Basic

• syntax
• variable
• for...loop
• condition
• function
• format / string operation
• module

Perl - File I/O

Open Function

• open(DATA, "+<file.txt"); or die "Couldn't open file file.txt, $!"

---

1 < or r Read Only Access

2 > or w Creates, Writes, and Truncates

3 >> or a Writes, Appends, and Creates

4 +< or r+ Reads and Writes

5 +> or w+ Reads, Writes, Creates, and Truncates

6 +>> or a+ Reads, Writes, Appends, and Creates

Sysopen Function

• sysopen(DATA, "file.txt", O_RDWR|O_TRUNC );

---

1 O_RDWR Read and Write

2 O_RDONLY Read Only

3 O_WRONLY Write Only

4 O_CREAT Create the file

5 O_APPEND Append the file

6 O_TRUNC Truncate the file

7 O_EXCL Stops if file already exists

8 O_NONBLOCK Non-Blocking usability

Close Function

• close(DATA) || die "Couldn't close file properly";

Reading and Writing Files

• getc Function
• read Function
• print Function
• Copying Files
• Renaming a file
• Deleting an Existing File
• Positioning inside a File tell seek Function
• File Information

---

-A Script start time minus file last access time, in days.

-B Is it a binary file?

-C Script start time minus file last inode change time, in days.

-M Script start time minus file modification time, in days.

-O Is the file owned by the real user ID?

-R Is the file readable by the real user ID or real group?

-S Is the file a socket?

-T Is it a text file?

-W Is the file writable by the real user ID or real group?

-X Is the file executable by the real user ID or real group?

-b Is it a block special file?

-c Is it a character special file?

-d Is the file a directory?

-e Does the file exist?

-f Is it a plain file?

-g Does the file have the setgid bit set?

-k Does the file have the sticky bit set?

-l Is the file a symbolic link?

-o Is the file owned by the effective user ID?

-p Is the file a named pipe?

-r Is the file readable by the effective user or group ID?

-s Returns the size of the file, zero size = empty file.

-t Is the filehandle opened by a TTY (terminal)?

-u Does the file have the setuid bit set?

-w Is the file writable by the effective user or group ID?

-x Is the file executable by the effective user or group ID?

-z Is the file size zero?

Perl - Directories

• opendir DIRHANDLE, EXPR # To open a directory
• readdir DIRHANDLE # To read a directory
• rewinddir DIRHANDLE # Positioning pointer to the begining
• telldir DIRHANDLE # Returns current position of the dir
• seekdir DIRHANDLE, POS # Pointing pointer to POS inside dir
• closedir DIRHANDLE # Closing a directory.

Perl - Error Handling

• The if statement
• The unless Function
• The ternary Operator
• The warn Function
• The die Function
• Errors within Modules
• The carp Function
• The cluck Function
• The croak Function
• The confess Function