Working with User Input in Bash

dudeman41465 · 06-02-2009, 02:22 PM

I've been using python/bash to help myself automate things for a long time, however I am curious. One reason I use python more is because I don't quite know how to work with user input in Bash, such as getting it to ask for input and wait, and then placing that user input into a command. Here's an example of a script I use from time to time for converting OGG video files into AVI. How could I write this same script in Bash? Keep in mind I am mostly self taught, so I am by no means an expert programmer.

Code:

#This script automates the process of converting an OGG video file
#to an AVI format file.  This script requires that you have mencoder
#installed.
import os
print ""
print "Welcome to your OGG Video Converter!"
print ""
print "This will convert OGG videos into AVI format."
print ""
def main():
    print "Please enter the filename of the video you wish"
    print "to convert, remember to include quotes around"
    print "the filename if it contains spaces."
    print ""
    infile=raw_input("Enter filename: ")
    print ""
    print "The converted video will be placed on your desktop."
    print ""
    newname=raw_input("What would you like to name the converted video? ")
    print ""
    print "The file %s is about to be converted to %s.avi."%(infile, newname)
    print ""
    raw_input("Press Enter to begin the conversion...")
    print ""
    os.system(('mencoder %s -o $HOME/Desktop/"%s".avi -oac mp3lame -ovc lavc')%(infile, newname))
    print ""
    raw_input("Conversion complete, press Enter to exit...")
def firstrun():
    if os.name!='posix':
        print "This program will only run in a Unix-based operating system"
        print "with the program 'mencoder' installed."
        raw_input("Press Enter to exit...")
    else:
        main()
firstrun()

colucix · 06-02-2009, 02:38 PM

User input is retrieved from the read built-in. Use read -p if you want to prompt a message to the user, for example:

Code:

read -p "Please enter the filename of the video you wish
to convert, remember to include quotes around
the filename if it contains spaces.

Enter filename: " infile

bigearsbilly · 06-03-2009, 05:02 PM

why all those print statements? it's awful.
don't do it.
I know python has better ways than that to do multi lines.

you can use select for input menus

Code:

echo who is your favourite beatle?
select choice in john paul ringo george
do

    echo you chose $choice
    break
done

ghostdog74 · 06-03-2009, 07:42 PM

Quote:

Originally Posted by dudeman41465

I've been using python/bash to help myself automate things for a long time, however I am curious. One reason I use python more is because I don't quite know how to work with user input in Bash,

that should not even be one of the reason why you choose Python over bash.

by the way, to print multiline

Code:

thestring = """
 this is a 
 multi line statement
 the end
"""

also, try to use subprocess module for calling external commands like mencoder