Hey guys....!

I am back here with my another blog. Today I attend another session of Linux workshop. This blog presents the topic covered on day 8 of the Linux workshop conducted by Mr.Pranav Jambare sir.

so, let's start with the contents of Day 8.

Contents

• While Loop

• Until Loop

• For Loop

• Command Line Arguments

While Loop

• If the condition remains satisfied the loop runs.

• The while loop repeatedly executes the commands inside the loop as long as the condition remains true.

• The while loop repeatedly executes the commands inside the loop as long as the condition remains true.

Syntax :-

    #Syntax 
while <command>
do
     statement executed if the command is true
done

Example :-

#!/bin/bash
a=0
while [ ${A} -lt 20 ]
do
    echo "number is ${A}"
    A = `expr ${A} + 1`
done

Until Loop

• If the condition remains unsatisfied the loops run.

• In shell scripting, the until loop is similar to the while loop, but it executes a block of code repeatedly until a certain condition becomes true

Syntax :-

    #Syntax 
until <condition>
do
    statement executed if the command is true
done

Example :-

#!/bin/bash
a=20
while [ ${A} -lt 0 ]
do
    echo "number is ${A}"
    A = `expr ${A} - 1`
done

For Loop

• It is a control flow statement for specifying iteration.

• The commands inside the loop are executed for each item in the list.

  Syntax :-

#Syntax 
for var in word1 word2..wordn              --(var=variable)
do
statements executed till element end
done

Example :-

#example
#!/bin/bash
for var in $(cat /root/names)
do
echo "${var}"
done

Command Line Arguments

• $1 $2 $3 :- Arguments passed

• $0 :- Name of the shell program

• $@ :- One by one argument passed

• $# :- Total number of arguments

• $* :- All arguments together

• $$ :- PID(Process ID) of current shell. (Actually the program PID can be achieve)

• $? :- Status of last command

• $! :- PID of last command.

#example
#!/bin/bash
for names in $1 $2 $3;
do
    echo "My name is ${name}"
    echo "My program name is $0"
    echo "$#"
    echo "$*"
    echo "$$ last prg pid"
    sleep 200
    echo "$? last comnd run"
    echo "$! last comnd pid"
done

#output
My name is Ayush
My file name is dynamic.sh
3
ayush aryan unmesh
5103 last prg pid
0 last comnd run
2637 last comnd pid

These important topics are covered on the day 8 of the Linux Workshop. I hope you enjoy it.

Thank you for reading the blog......!!!!