bashScript

Contains bash script files for beginers

• echo : Works like print statement to print something on the terminal

  • To forget or not using new line character by default you have to use

    echo -n "second line"
    

  • To allow special character to work use echo -e "\nSpecial character"

• To set multi line comment

  • Colon [:] Should be present at starting after ward put all comment in single quotes

    : 'put all data like this'
    

• To do mathematical work type like this

  ((result=$num/17))
  

• To print mathematical output inside the echo type:

  • After echo give a pipe and type "bc"

     echo $num/17 | bc
    

• To get decimal value put -l afterwards

  echo $num/17 | bc -l
  

• To concat the two string variable

  result="$var1 $var2"      
  

• To get the substring from the whole string

   str="hey World"
   subString=${str:0:2}
  
   # 0 here is the starting position
   # 2 is the number of characters
  

• Checking multiple if condition:

   if [[ ($var -le 0  && $rand -eq 5) ]];
  
   # If you put || in place of && it will work as OR command 
  

• To get several arguments from command line:

• [$#] : Used to set multiple arguments

   args=$#
    var=$1
    var2=$2
  

• Until Loop is different from while:

• Until loop will run till the condition become false. On the other side while will run till the condition become false

• Calling function which return some value

   AddReturn()
   {
       ((out=$1+$2))
       echo "inside the loop"
       echo $out
      }
  
  # calling the function here
   
   valOutput=$(AddReturn 10 2)
   echo $valOutput
  

• We have two type of environment variable

• Shell variable

• Environment variable

   export name="value"
  
   [Will only be present locally mean for that terminal only]
  

• export name="val"

  • [Put that in ~/.bashrc file to make it permanent]

• Alias : It is used to set the small name to everthing. Save this permananetly to .bashrc file

   alias name="cd /home/tushar/Desktop"
  

• Wildcards: Are used to ease your work

   cp {*.mp3,*mp4} /destination
  

• Run multiple command

• This will run the command as random

  cp ; ls ; pwd
  

• To run the command in sequence what need to what to get it complete use:

  cp && pwd && ls