Page Comparison

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FOO="Hello world!"
echo "The value of variable 'FOO' is \"$FOO\""   # Escape the double quotes inside double quotes
echo "The value of variable 'FOO' is"' "'$FOO'"'   # Single-quoted text after double-quoted text

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date          # Calling the date command just displays date/time information
echo date     # Here "date" is treated as a literal word, and written to output
echo `date`   # The date command is evaluated and its output replaces the command

today=$( date );          echo $today  # environment # Assign a string including today's date to variable "today" is assigned
today's date
today="Today is: `date`"; echo $today  # "today" is assigned a string including today's date

The slightly odd syntax $(<some command>), is equivalent to `<some command>`, and can be easier to read when the command to be evaluated is complex.

echo "Today is: `date`"
echo "Today is $(date)"

Exercise 3-5

How would you output this text using a command to calculate the number of lines: The haiku.txt file has 11 lines

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ls haiku.txt xxx.txt 1> stdoutout.txt 2>stderr2>err.txt
cat stdoutout.txt   # Displays "haiku.txt"
cat stderrerr.txt   # Displays "ls: cannot access 'xxx.txt': No such file or directory"

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1. Use a command-line program that lets you enter/edit text in a Terminal window (e.g. nano, vi/vim, emacs)
   1. nano is extremely simple and is a good choice as a first local text editor
      • warning: nano has a tendency to break long single lines into multiple lines
   2. vi and emacs are extremely powerful but also quite complex
      • emacs reference sheet: https://www.gnu.org/software/emacs/refcards/pdf/refcard.pdf
      • vi reference sheet: http://www.atmos.albany.edu/daes/atmclasses/atm350/vi_cheat_sheet.pdf
2. Use a text editor or IDE (Integrated Development Environment) program that runs on your local computer but has an SFTP (secure FTP) interface that lets you connect to a remote computer
   
   • E.g.,Komodo IDE (Windows & Mac) or Notepad++ (Windows). Both are no-cost.
     
   • Once you connect to the remote host, you can navigate its directory structure and edit files.
   • When you open a file, its contents are brought over the network into the text editor's edit window, then saved back when you save the file.
3. Use software or protocols that allow you to "mount" remote server directories
   
   • Once mounted, the remote storage appears as a local volume/drive.
     • Then, you can use any text editor or IDE on your local computer to open/edit/save remote files.
   • Software programs that can mount remote data include ExpanDrive for Windows or Mac (costs $$, but has a free trial), TextWrangler for Mac.
   • Remote file system protocols include Samba (Windows, Mac) and NFS (Linux)

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