Correct.

Again: all these devices in scripts work (at least in principle) on the command line too and everything you write on teh commandline could come from a script. In fact every shell is a "command language" which you either type in by hand or have typed in from a script file. A script file is basically just a file with stored commands you don't have to type again should you need them a second time.


You mean "{"? It is for command grouping. Basically everything between "{ ... }" works like a single command from the outside. It is like you could write a script, give it a name and then use this script in another script like any other command. This works the same, just inside scripts.

Simple: to be easier readable (for humans). If you have a loop (for ... done or while ... done) or a branch (if ... else ... fi or case ... esac) you indent the body of this to see easily what this body of the construct is. For the shell executing the command it makes no difference at all. You can write:

Code:

 while <condition> ; do
     command1
     command2
     command3
done

and the definition of the loop as well as the body immediately will stand out. This:

Code:

 while<condition> ; do command1; command2; command3; done

is syntactically the same but is a lot harder to find out what is loop definition and what is its body.


Very well. There is a "-exec" flag for find, which you could use. It takes a "command template" where the filename "find" has found is represented by "{}". Suppose you have a command

Code:

cmd /path/to/myfile.txt

and you want to execute this command with every txt-file in all subdirectories of "/there/too". You would write:

Code:

find /there/too -type f -name "*txt" -exec cmd {} \;

"find" will find all the filenames and for each filename found that way execute the command up to "\;" (this signifies the end of the template command) with "{}" replaced by the actual filename. You might find this device extremely useful and - i can promise - once you got the hang of it you can easily outperform every filemanager there might be. Unix aficionados are not command line fetishists because they are masochists, but because they can type in seconds what you can do with a mouse in hours.


We have a several "vi" resources here, threads where people tried to explain its usage in general or specific aspects of it. "vi" is most times a "love on third sight". First, you think it is overly complicated, the first half year you use it you think its giving you the third degree and after this time you start missing its features in every other program you type more than two keystrokes in.

Here is how to make the unvisible characters visible in "vi":

open the file. Hit "<ESC>" (maybe repeatedly, it can't hurt) to make sure you are in command mode. Press ":". A line with ":" at the beginning will appear in the last line of the screen. Enter "set list" and press <ENTER>. The line will disappear and you will see the non-printing characters now. Press ":" again and enter "set nolist" to switch that mode off or simply leave the editor. These characters will appear and have the following meaning:

Code:

^I     tab character
$      line end, Unix style
^M$    line end, DOS/Windows style

Notice that "^I" and "^M" are ONE character, as you can see when you pass over them with the cursor.

To remove the DOS line ends, you can do the following magic:

Again, from the command mode (<ESC>, you remember, will always take you there) press ":" and type:

Code:

1,$ s/^M$//

Enter the "^M" by pressing "<CTRL>-<V>" (take the next input character verbosely) and then either "<CTRL>-<M>" or "<ENTER>". You will notice that the "^M" appears.

You can do this with "list" mode set and you will see the "^M"s at the line ends (ALL line ends!) disappear. The command says: from the first to the last line ("1,$") substitute ("s") a ^M character, followed by a line end ("/^M$/") with nothing ("//").

Very good. in Unix every directory has its rationale and purpose and this is even (informally) standardized (we use the word "canonical" for this type of informal standard). Indeed "/usr/local/bin" is the directory where executable files which do not belong to the OS go (OS executables go to "/usr/bin"). "/usr", btw., is for "Unix Software Resources", even if it is usually pronounced like "user".

LOL! Well, i think christians have burned already enough things in history, so it might even work if it doesn't warm up enough. Bishop Theophilus of Alexandria is quoted to have said, while burning down the library of Alexandria, that the books in there either agree with the bible and are superfluous or disagree with the bible and are rightfully burned. I am not divinely inspired to the same degree as this venerable bishop, but i can suggest a book about (Korn) shell and shell programming. It helps best, btw., if being read instead of being burned:

Barry Rosenberg, Korn Shell Programming Tutorial

You will find the read informative as well as very entertaining.

Exactly. This is the common method of dealing with blanks, because blanks are the shells default way of separating things. If one doesn't the blank (or any other) character to do that you use quoting.

I hope this helps.

bakunin