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davenull wrote:what means redirection? After starting by the icon I already execute in the terminal.
Is there perhaps a command like getchar() in a bash script to wait for ENTER before closing the window?

davenull wrote:@jamesh:
Although this is OT and it would be better to maintain this discussion by PMs:
yes I know and I do what's possible to me as a non-English speaking hobbyist and just a complete beginner to Linux.

so Is there perhaps a command like getchar() in a bash script to wait for ENTER before closing the window?

man read

READ(2)                    Linux Programmer's Manual                   READ(2)

NAME
       read - read from a file descriptor

SYNOPSIS
       #include <unistd.h>

       ssize_t read(int fd, void *buf, size_t count);

QuietZone wrote:

man read

Heh heh - that doesn't do much that is useful:

Code: Select all

READ(2)                    Linux Programmer's Manual                   READ(2)

NAME
       read - read from a file descriptor

SYNOPSIS
       #include <unistd.h>

       ssize_t read(int fd, void *buf, size_t count);

And therein actually is the problem with man pages when you are actually trying to learn something (as opposed to just needing to look up a specific piece of information).

The problem is particularly acute when you are trying to learn shell, because the individual commands don't have their own man pages (*). It is all in "man bash" (or whatever shell you are using). I've actually gotten pretty adept at doing "man bash" (which is enormous) and finding the specific thing I need (the "xxx" command and/or the --fooBaz option), but that in and of itself is a skill that newcomers won't have (and will need to develop).

(*) Note that in C, they more or less do. I.e., if you want to know what "read" does (in C), you can, indeed, do "man read" and get the scoop.

jamesh wrote:man bash

then about line 3600 for explanation of the 'read' command in bash. Or use google for examples.

pi@raspi3 ~ $ help read
read: read [-ers] [-a array] [-d delim] [-i text] [-n nchars] [-N nchars] [-p prompt] [-t timeout] [-u fd] [name ...]
    Read a line from the standard input and split it into fields.
    
    Reads a single line from the standard input, or from file descriptor FD
    if the -u option is supplied.  The line is split into fields as with word
    splitting, and the first word is assigned to the first NAME, the second
    word to the second NAME, and so on, with any leftover words assigned to
    the last NAME.  Only the characters found in $IFS are recognized as word
    delimiters.
    
    If no NAMEs are supplied, the line read is stored in the REPLY variable.
    
    Options:
      -a array	assign the words read to sequential indices of the array
    		variable ARRAY, starting at zero
      -d delim	continue until the first character of DELIM is read, rather
    		than newline
      -e		use Readline to obtain the line in an interactive shell
      -i text	Use TEXT as the initial text for Readline
      -n nchars	return after reading NCHARS characters rather than waiting
    		for a newline, but honor a delimiter if fewer than NCHARS
    		characters are read before the delimiter
      -N nchars	return only after reading exactly NCHARS characters, unless
    		EOF is encountered or read times out, ignoring any delimiter
      -p prompt	output the string PROMPT without a trailing newline before
    		attempting to read
      -r		do not allow backslashes to escape any characters
      -s		do not echo input coming from a terminal
      -t timeout	time out and return failure if a complete line of input is
    		not read within TIMEOUT seconds.  The value of the TMOUT
    		variable is the default timeout.  TIMEOUT may be a
    		fractional number.  If TIMEOUT is 0, read returns immediately,
    		without trying to read any data, returning success only if
    		input is available on the specified file descriptor.  The
    		exit status is greater than 128 if the timeout is exceeded
      -u fd		read from file descriptor FD instead of the standard input
    
    Exit Status:
    The return code is zero, unless end-of-file is encountered, read times out
    (in which case it's greater than 128), a variable assignment error occurs,
    or an invalid file descriptor is supplied as the argument to -u.

davenull wrote:thanks - 1st of all I did not even know what you mean by
read
or
man read

I interpreted it as
"dude, study!"

I never assumed "read" to be the command I was looking for (or I had to search or to look for), in my MSDOS days I was using "pause" for this purpose, and as Linux is C-based I had more expected something C-command-like as getchar, getch, getc, while not kbhit, or even cin.

Then, 2nd, Linux is a big mess to me. To me an operating system is only good if it's working underneath and if one doesn't even perceive it all.

Ok, I need certain simple commands, but in the first line I want to programm my map-and-explore-robot and my neural nets in C (as I have already established by Arduino or whatever) - but not the entire operating system itself. Surely I will learn step by step and my skills will improve as times go by, but that's not what I'm currently starting with.

So I would appreciate if you provided just 1 line I had to write out of the 30 trillion read options hidden in perhaps 3600 million manual lines which one to take to simply wait for an keypress and/or ENTER before the terminal window would close automatically on it's own by it self...

Ok, I need certain simple commands, but in the first line I want to programm my map-and-explore-robot and my neural nets in C (as I have already established by Arduino or whatever) - but not the entire operating system itself. Surely I will learn step by step and my skills will improve as times go by, but that's not what I'm currently starting with.
...
So I would appreciate if you provided just 1 line I had to write out of the 30 trillion read options hidden in perhaps 3600 million manual lines which one to take to simply wait for an keypress and/or ENTER before the terminal window would close automatically on it's own by it self...

How much do you learn if someone simply gives you the exact line of bash you want? Not a lot, and you'll need to ask again the next time and the next time. But read up on it, and you learn.