Shell commands read data and output data

Several ways the shell script reads data:
1. keyboard input, default
2. read from the file
3. Pass through Pipeline command

Functions of Echo:
C: No Line change
F: Paper Feed
T: Jump lattice
N: Line Wrap
Represents an escape, for example: "/dev/rmt0" translates to, "/dev/rmt0"

READ: Reads information from a line of text in a keyboard or file and assigns it to a variable.
[Development]/>read Name
Hello I am a regular user
[Develop]/>echo $name
Hello I am a regular user
[Development]/>

Cat: Function, 1. Display the contents of the file, 2. Create a file, 3. Display control characters.
1. Display the contents of the file
Cat FileName | More
Cat FileName | Pg
2. Create a file
Cat > FileName
3. Display control characters
cat-v filename

Pipe: The output of one command can be passed to another command as input through a pipe.
Form: Command 1 | Command 2
For example:
[Development]/usr/xxxx/ytcclb>who | awk ' {print ' t ' $} '
XXXX ttyp0
XXXX TTYP1
XXXX TTYP2
...
XXXX Ttyp55
[Development]/usr/xxxx/ytcclb>df-k | awk ' {print $} ' | Grep-v "FileSystem"
/dev/root
/dev/boot
[Development]/usr/xxxx/ytcclb>df-k | awk ' {print $} ' | Grep-v "filesystem" |sed s '//dev///g '
Root
Boot
[Development]/usr/xxxx/ytcclb>

Tee command
Function: Transfer one copy of output to standard output and another copy to the corresponding file.
Tee-a file
-A: Append to end of file.
[Development]/usr/xxxx/ytcclb>who | Tee who.out
Save the data that the WHO command finds to the Who.out file.

File redirection:
Command > FileName redirect standard output to a new file
Command >> filename REDIRECT standard output to a file (append)
Command 1 > Fielname redirect standard output to a file
Command > FileName 2>&1 redirects the standard output to a file with standard errors
Command 2 > FileName redirect standard errors to a file
Command 2 >> filename REDIRECT standard output to a file (append)
Command >> filename 2>&1 redirects the standard output to a file (append) with the standard error
Command < filename >filename2 the command command to the filename file as the standard input,
Use filename2 file as standard output
command < filename input command to filename file as standard
Command << delimiter reads from the standard input until it encounters the delimiter delimiter
Command <&m the file descriptor m as the standard input
Command >&m redirects standard output to the file descriptor m
Command <&-turn off the standard input

REDIRECT Standard output
1. Append the output of many commands to a file
Ls-l | grep ^d >>files.out
LS account* >> files.out

[Development]/usr/xxxx/ytcclb>ls-l null.txt
-rw-r--r--1 xxxx Group 3 Nov 16:07 null.txt
[Dev]/usr/xxxx/ytcclb> chmod u +x null.txt
Chmod:WARNING:cannot access +x:no such file or directory (Error 2)
There are spaces between U and +x!
[Develop]/usr/xxxx/ytcclb>chmod u+x null.txt
[development]/usr/xxxx/ytcclb>ls-l null.txt
-rwxr--r--1 xxxx Group 3 N OV 16:07 null.txt