🚀 go-pugleaf

From article <89345.110313MHS108@PSUVM.BITNET>, by MHS108@PSUVM.BITNET (Mark Solsman):
> 
>    Can any one out there explain how to use the redirection and the pipeline
> features with ms-dos? 
What follows in not technical. It just gives short examples of how they
can be used, and warnings about when they can't. It is fairly long.

John Baird, Naval Ocean Systems Center, San Diego, CA USA
--------
From HELPSB, a DOS VMS-like help utility's files:
******** Information about |(piping) *******
To pipe (send, channel, direct) the output of one command into another command.

Output from a command that would normally appear on the screen can be used
as input to another command (that would normally get its input from the 
keyboard) by piping it. Piping is controlled by the use of the vertical bar 
(|) character. Some versions of DOS may not support the use of piping in BATCH 
files. 

If a text file, maybe some sort of document, had 10,000 lines in it, it could 
be displayed on the screen one full screen at a time, with the command

	TYPE BIGFILE.TXT | MORE

If a directory contained 20 entries, to get a listing of the contents of the 
directory in alphabetical order, the command

	DIR | SORT

could be used. If the directory had 120 entries, an alphabetical display one 
full screen at a time could be obtained by the command

	DIR | SORT | MORE
	ECHO Hello >> TST.TXT

will redirect the string "Hello" from the screen to the file TST.TXT. If 
TST.TXT did not previously exist, this will create it. 

	SORT < RANDOM.TXT >> SORTED.TXT

will redirect input from the keyboard to come from the file RANDOM.TXT and 
redirect output to the screen to be added to the end of the file SORTED.TXT.

	TYPE CON >> EXISTING.TXT 

will read everything entered from the keyboard (until a Ctrl-Z is entered) and 
add it to the end of file EXISTING.TXT, rather than displaying it on the 
screen. Another way to to the same thing is with 

	COPY EXISTING.TXT+CON

It may sometimes appear that >> didn't work. If a file has a Ctrl-Z character 
in it, >> will still add to the end of the file, AFTER the Ctrl-Z. Some 
editors, and the DOS TYPE and COPY /A commands, quit when they encounter the 
first Ctrl-Z.
    MORE < NEW.TXT

will redirect input which would normally come from the keyboard to come from 
the file NEW.TXT. MORE will still display its output on the screen. 

    SORT < RANDOM.TXT > SORTED.TXT

will redirect input from the keyboard to come from the file RANDOM.TXT
and redirect output to the screen to the file SORTED.TXT.

******** Information about < or > or >> (redirection) *******
To change the normal destination or source of input or output for a command
is done by redirection. Input that normally comes from the keyboard for a
command can be redirected to come from a file by the < symbol (INPUT gives
examples). Output from a command that normally goes to the screen can be
redirected to a file by the > symbol (OUTPUT gives examples) or >> symbols
(APPEND gives examples).

Device names are really useful with redirection when used by DOS commands 
like COPY, ECHO, ESC, SORT and TYPE. Separately purchased programs may or
may allow the use of redirection. If you encounter problems or erratic 
behavior in the use of redirection, it may be because the number of files 
that can be open at one time is set too low. This number is specified on 
the FILES line in the CONFIG.SYS file. 

******** Information about > (output) *******
	ECHO Hello > TST.TXT

will redirect the string "Hello" from the screen to the file TST.TXT. If 
TST.TXT already exists, its previous contents will be lost. Use >> to add
to an existing file.

	SORT < RANDOM.TXT > SORTED.TXT

will redirect input from the keyboard to come from the file RANDOM.TXT
and redirect output to the screen to the file SORTED.TXT.

	COPY OLD NEW > NUL

will copy the file OLD in the current directory to the file NEW, and the usual
COPY message "1 File(s) copied" will not appear on the screen. It will be
redirected to the NUL device. This is a way to reduce the number of messages 
that appear on the screen while a batch file is being executed.

	REM > EMPTYFIL

will create the file EMPTYFIL, a file that is empty (it has no data in it
and a DIR command will show its size is zero).

	ECHO remark 
	PAUSE > NUL
will redirect the usual 

	Strike any key when ready...

message to NUL, allowing a remark of your choosing to appear on the screen.

******** Information about < (input) *******
    MORE < NEW.TXT

will redirect input which would normally come from the keyboard to come from 
the file NEW.TXT. MORE will still display its output on the screen. 

    SORT < RANDOM.TXT > SORTED.TXT

will redirect input from the keyboard to come from the file RANDOM.TXT
and redirect output to the screen to the file SORTED.TXT.

******** Information about >> (append) *******
	ECHO Hello >> TST.TXT

will redirect the string "Hello" from the screen to the file TST.TXT. If 
TST.TXT did not previously exist, this will create it. 

	SORT < RANDOM.TXT >> SORTED.TXT

will redirect input from the keyboard to come from the file RANDOM.TXT and 
redirect output to the screen to be added to the end of the file SORTED.TXT.

	TYPE CON >> EXISTING.TXT 

will read everything entered from the keyboard (until a Ctrl-Z is entered) and 
add it to the end of file EXISTING.TXT, rather than displaying it on the 
screen. Another way to to the same thing is with 

	COPY EXISTING.TXT+CON

It may sometimes appear that >> didn't work. If a file has a Ctrl-Z character 
in it, >> will still add to the end of the file, AFTER the Ctrl-Z. Some 
editors, and the DOS TYPE and COPY /A commands, quit when they encounter the 
first Ctrl-Z. If a file has internal Ctrl-Z characaters in it, the EDLIN 
command can be used to remove them (see the EDLIN HINTS CONTROL_CHARACTERS 
topic.)