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A shell process is a process that executes other processes, but when executing a command, the shell process instructs the kernel to execute the specified program separately as another process and write the output to the terminal
.
With command options, we can modify the behavior of command execution.
Command line options can be divided into
short command line
options
and
long
command line options . Short command line options are composed of
letters
, long command line options are composed of
words
.
Short command line options use
a single
dash "-" before the option, and long command line options use a
double
dash "--" . If an option's argument needs to be entered after the option, use a
space
, while long command-line options use
an equals sign
"=" to concatenate options and arguments .
We can get help information for a command by adding the option "--help", "-h" or "-?" after the command.