Coding Bash vs. Perl vs. Python (by Evan Liu)

Topics about command line

Command line: variables from command line 


		  
		  

		  
Tasks:
1.1. print the array of the argments 
2.2. print individual arguments
3.3. loop over the arguments
4.4. print the script name
5.5. print the script path
6.6. print the number of arguments
		  

		       
          
          

             
             

		     

                Bash
                Perl
                Python			   
		     

             
              

                
  1. cat>/tmp/tst <<"EOF"

  2. #1.1. print the array of the argments 

  3.   echo "$@"

  4.   echo "$*"

  5. 

  6. #2.2. print individual arguments

  7.   echo $1 $2 $3

  8.   echo "the last argument: ${!#}"

  9. 

  10. #3.3. loop over the arguments

  11.   for i in "$@";do echo $i;done

  12. 

  13. #4.4. print the script name

  14.   echo $0

  15. 

  16. #5.5. print the script path

  17.   echo `readlink -f $0`

  18. 

  19. #6.6. print the number of arguments

  20.   echo $#

  21. EOF

  22. bash /tmp/tst arg1 arg2 arg3

  23. 

  24. -------output----------



  1. arg1 arg2 arg3

  2. arg1 arg2 arg3

  3. arg1 arg2 arg3

  4. the last argument: arg3

  5. arg1

  6. arg2

  7. arg3

  8. /tmp/tst

  9. /tmp/tst

  10. 3



                
  1. #  or cat>/tmp/tst<<<'print "@ARGV\n"'; 

  2. cat>/tmp/tst<<'EOF'

  3. print "@ARGV\n";

  4. print "$ARGV[0] $ARGV[1] $ARGV[2]\n";

  5. print "$_\n" foreach(@ARGV);

  6. print "$0\n";

  7. print ((0+@ARGV),"\n");

  8. print scalar(@ARGV), "\n";

  9. EOF

  10. perl /tmp/tst arg1 arg2 arg3

  11. 

  12. -------output----------



  1. arg1 arg2 arg3

  2. arg1 arg2 arg3

  3. arg1

  4. arg2

  5. arg3

  6. /tmp/tst

  7. 3

  8. 3



                
  1. #  or echo -e "import sys\nprint str(sys.argv)" > /tmp/tst

  2. cat >/tmp/tst<<'EOF'

  3. import sys

  4. import os

  5. #1.1. print the array of the argments 

  6. print str(sys.argv);

  7. 

  8. #2.2. print individual arguments

  9. print sys.argv[1],sys.argv[2],sys.argv[3]

  10. 

  11. #5.5. print the script path

  12. print os.path.basename(__file__)

  13. print sys.path[0]

  14. EOF

  15. python /tmp/tst arg1 arg2 arg3

  16. 

  17. -------output----------



  1. ['/tmp/tst', 'arg1', 'arg2', 'arg3']

  2. arg1 arg2 arg3

  3. tst

  4. /tmp



              

             
            
 
          

          

		  

        
          

		  
Command line: use getopt(s) to handle the command line 

		  

		  
		  

		  
Tasks:
1.1. ceate a script file to handle commandline with getopt(s)
2.2. run the script with some arguments
		  

		       
          
          

             
             

		     

                Bash
                Perl
                Python			   
		     

             
              

                
  1. #  getopts

  2. cat>/tmp/tar.sh<<"EOF"

  3. declare -A myopts

  4. usage() { 

  5. echo "Usage: $0 [-zxvf <fname>] [-C <dir>]" 1>&2

  6. exit 1

  7. }

  8. while getopts "xvzf:C:" opt "$@"; do

  9.   case "${opt}" in

  10.     z|x|v|C|f) myopts["${opt}"]=${OPTARG} ;;

  11.     *) usage ;;

  12.   esac

  13. done

  14. shift $((OPTIND-1))

  15. for key in ${!myopts[@]}; 

  16.   do echo "$key => ${myopts[$key]}"; done

  17. EOF

  18. bash /tmp/tar.sh -zxvf ~//tmp/tst.tar.gz -C /tmp

  19. 

  20. -------output----------



  1. C => /tmp

  2. f => /home/neutrino0717//tmp/tst.tar.gz

  3. v => 

  4. x => 

  5. z =>



                
  1. #  getopts

  2. cat>/tmp/tar.pl<<"EOF"

  3. use Data::Dumper;

  4. use Getopt::Std;

  5. #  read options

  6. getopts('C:zxvf:', \%opts); 

  7. print "the options are:\n";

  8. print Dumper (\%opts);

  9. EOF

  10. perl /tmp/tar.pl -zxvf ~//tmp/tst.tar.gz -C /tmp

  11. 

  12. -------output----------



  1. the options are:

  2. $VAR1 = {

  3.           'z' => 1,

  4.           'C' => '/tmp',

  5.           'v' => 1,

  6.           'x' => 1,

  7.           'f' => '/home/neutrino0717//tmp/tst.tar.gz'

  8.         };



                
  1. #  getopt

  2. cat>/tmp/tar.py<<"EOF"

  3. import sys, getopt

  4. argv=sys.argv[1:]

  5. try:

  6.   opts = getopt.getopt(argv,"zxvf:C:")

  7. except getopt.GetoptError:

  8.   print "Usage: "+sys.argv[0]+" [-zxvf <fname>] [-C <dir>]"

  9.   sys.exit(2)

  10. print opts

  11. EOF

  12. python /tmp/tar.py -zxvf ~/tmp/tst.tar.gz -C /tmp

  13. 

  14. 

  15. -------output----------



  1. ([('-z', ''), ('-x', ''), ('-v', ''), ('-f', '/home/neutrino0717/tmp/tst.tar.gz'), ('-C', '/tmp')], [])