Symbolic Link vs Alias

A symbolic link is *not* an alias. A symlink (symbolic link) is in the filesystem so all of the layers of the OS can use symlinks. This includes Carbon, Cocoa, Java, and BSD apps. Alias files are Finder-specific concept. Aliases are not used by the rest of the system. Only the Finder deals with aliases. At the Finder level, aliases and symlinks are similar, but symlinks are far more versatile and used in pretty much every flavor of *nix.

FTP Command Line and Automation

The ftp command that runs on a Mac is similar to that from any other platform, including Windows – and not much has changed with regard to FTP for a long, long time. When using FTP you will login to an FTP server, then issue some commands, one of which will kill your session to the host. The commands you issue during an FTP session are issued in an interactive mode of the shell, where you are actually running them against the target server
  • ls – list the contents of a directory on the FTP server
  • cd – change the working directory on the FTP server
  • pwd – show the current directory on the FTP server
  • get – download files from the FTP server
  • put – upload files to the FTP server
  • account – include a password with your login information
  • bye – terminate an ftp session and close ftp (or use disconnect to simply terminate a session)
  • bell – make a cute sound after each file transfer is done
  • chmod – change permissions
  • delete – your guess is as good as mine (OK, you got me, it’s to delete a file off the server)
  • glob – enable globbing
  • hash – only functional in Amsterdam
  • help – get help
  • lpwd – print the local working directory for transfers
  • mkdir – create folders on the FTP server
  • rmdir – delete folders from the FTP server
  • newer – only get a file if it’s newer (great for scripting synchronizations)
  • nmap – use positional parameters to set filenames
  • passive – use FTP passive mode
  • prompt – allows the use of letters to automate answers to prompts
  • rate – limit the speed of an upload or download
Notice the similarity between FTP commands and Mac OS X commands! This continues into repetition: in Mac OS X you can build commands to run automatically when you open a new shell. Using a netrc file you can do the same with opening an FTP session. The ~/.netrc file (or just netrc) is a text file that, like .bash_profile, lives in your home directory (aka – ~). The .netrc file allows FTP to perform automatic logins to FTP servers based on the name (not that there aren’t subcommands to do the same, but it allows you not to insert the password into your history or script). Like .bash_profile, the .netrc will need to be created per user, which can be done with the following:
touch .netrc
Because you’re going to put password information in there, let’s also restrict who can look at it:
chmod 700 .netrc
Now open your shiny new .netrc file and create a block of settings for each FTP server you want to automate access for. This information will be the ftp server (machine), the username (login) and the password (yup, that’s the password). For example, the entire file could be:
machine krypted.com login ftpkrypted password kryptedsupersecrethax0rpassword
You can also connect to a server using the following format with each command with each command:
ftp://username:password@servername:port
Now that you can login without issue, let’s write a script to perform some routine tasks, such as keeping a web site up-to-date.
#!/bin/bash ftp -d krypted.com << ftpEnd prompt cd /Library/WebServer/Documents put “*.html” put “*.php” cd /Library/WebServer/Documents put “*.png” quit ftpEnd
Or Downloading documents off of a website:
#!/bin/bash ftp -d krypted.com << ftpEnd prompt cd /My/Documents get “*.doc” quit ftpEnd
There are also some variables that you can use in the prompt:
  • %/ – the current working directory of the FTP server
  • %M – the hostname of the FTP server
  • %m – the hostname only up to the .
  • %n – the username used for the FTP server
Finally, you can also define macro’s in your .netrc file using macdef.