Shell Scripting Tutorial for Beginners 20 - use FOR loop to execute commands Video Lecture | Complete Linux Course: Become a Linux Professional - Software Development

hey guys welcome to the next video on
shell scripting tutorial for beginners
in the last video we have seen how to
use for loop in shell scripting now in
this video we will see how we can use a
for loop with some command and we will
see some examples to understand this
better so this is the basic syntax we
have seen in the last video so we use
for keyboard and then command or any
variable here and then we use the
keyword in and then after the keyword we
give some input in the form of some
lists or some commands right and then we
use do and done keyword and then we use
some come on to you know execute the
item value right which is here okay so
let's see how we can use commands here
so we can give our list of commands in
order to execute them so for example I
can give LS here and then I can give the
PWD for present working directory and
for example I give the date command to
know the date right so this is the list
of command and these commands will be
executed one by one so first of all the
LS command will be executed and then the
PWD command will be executed and then
the date command will be executed right
so let's see how this works so what I'm
going to do is I am going to echo for
example online and then I'm going to
print the name of the command
so let's print the name of the command
first and then we are going to execute
the command itself so how we can execute
the command itself we can execute it
without the echo command so echo command
is going to give you the name of the
command and then this is going to
actually execute that command okay so
let's run the script and let's see what
happens
so I'm going to run my script and this
is the output so the LS command is
giving us all these LS command values
right and then the PWD command is going
to give us this output and the date
command has given us this output right
so we can execute a number of commands
like this and they will be executed one
by one using this method right now let's
take some practical example also so for
example I'm in my home folder right now
and then I want to print all the
directories which are there in my home
folder for example right so let me do LS
minus a here and I can see there are
some directories here and I want to
print all the directories which are
there in this folder so I'm going to
clear the terminal first of all and then
let's write the code so here I can use
Astrix and Astrix means here that I want
to iterate over each and every file or
directory in this directory which I am
currently in right
so as strix is a wild-card and hopefully
you know how it works and then what I'm
going to do is instead of this code in
the do and done keyword we will first of
all use the if statement and we will
evaluate the value of command and
command is not appropriate keyword here
for example I will say item here right
so whatever item is iterated or whatever
item we have using this Asterix keyword
then we will evaluate if it's a
directory or not and if it's a directory
then we will print it so we will use - D
for this and then the name of the item
right and then we use the keyword then
as we do with the if-else conditions and
then fi - n
viii right and in here we will just echo
this directory name okay so just right
echo and then the name of the item so
what it's not going to do this Astrix
command it's going to see all the items
which are there in this directory it can
be file or it can be a directory name
and then we are checking using this code
whether this is a directory or a file
and if it's a directory then we will
print the name of it okay so let's run
the script and let's see what happens
and we run the script and you can see
it's giving us all the directory names
so this is the name of the directory
name of the directory name of the
directory and then all the name of the
directories right now in this output we
can also see this warning or error also
here and let's see why this error is
coming so I'm going to open this
directory which is printing this output
and I can see there is a file name and
this file name has you know the keywords
then this file name has a qrt function
is da so there are four keywords
separated by spaces here right and now
our script is confused that these names
are separate or these names is the name
of one file so for example I will delete
this file name and let's run the script
once again so let me run it and now it
prints all the directories like this
okay so let me clear the terminal and
for example I just want to print all the
files so instead of using - tea I can
use - f or choosing all the files and
I'm going to run the script once again
and now it prints all the files which
are there in this directories okay so in
this way we can use commands with for
loop I hope you enjoyed this video
please read comments
and bye for now