103.1 Work on the command line

PID - Which means

What is the proccess with PID 1

two processes of the same application receives PIDs ______________

How to know what shell am I using?

Internal command is a command embedded on ____________

in order to execute external commands, what variable shell should search location info?

which command shows if a program is internal or external

#echo $PATH

/desktop/script.sh
Is it an absolute or relative path?

/home/desktop/scripts/script.sh
Is it an absolute or relative path?

/etc/init.d/script.sh
Is it an absolute or relative path?

How create a variable in shell?

How export variables in shell?

How create and export variable, in order to other shells sessions can see this variable data?

Which command shows all variable values?

Which command shows just external variables values?

An user opened a new shell and executed an external program without export. He received an error, why?

How shows the value of a variable in shell?

Which variable shows the values as the command #history?

Which variable shows the length of the return of command #history

$HISTSIZE

$HISTFILESIZE

$HOME

$HOSTNAME

$LOGNAME

$PATH

$PWD

$USER

$$
$!
$?

a proccess was executed with success, what number its returns?

#echo ~

#echo ~nameuser

$PS1

$OLDPWD

How execute three commands in the same line separating with a char?
# clear date ls

&&

||

#!!

#!19

#!uname

how to clear HISTFILE?

Can I read the HISTFILE from another user being a normal user?

How to search a command in history?

how command provides a detailed view of other command which includes NAME, SYNOPSIS, DESCRIPTION, OPTIONS, EXIT STATUS, RETURN VALUES, ERRORS, FILES, VERSIONS, EXAMPLES, AUTHORS and SEE ALSO

#man -k "string"

#whatis

#apropos

Which command returns system information?

Which command returns exactly the following info:
linux version, compilation date and kernel version

How to create a nickname to a command?
like the nickname of "cat" is "tom", then, when I use "tom" in shell, the system translate to "cat"

#echo *

#echo "*"

#echo '*'

What is the difference between
#echo "*"
#echo '*'

#echo "Curso Linux"
#echo Curso Linux
#echo Curso \ \ \ \ \ \ \ Linux
#echo "Curso Linux"

Which command we can use to get a command path?

How we get the release of kernel?