Linux scripting

northy_ie · 11-08-2005, 01:56 AM

Hi all

Basically, I want to have a script, that runs wget to download and backup some files off my webserver.
I've been trying to "add" a number and run it in a loop, but unfortunately, the leading zero's were gone after that.
This is the script, that should be run:

# !/bin/sh
# Backup files from webserver
#echo backing up files..
NUMBER="0001"
echo wget "h**p://shadow/edata/ed"$NUMBER".inf" (can't post the url due to forum restrictions)

The next file, it should try to get via wget is 0002, 0003, 0004, you get the point

the file range is currently 0001 - 0250..
Would any of you have an idea of how to get that up and running?

Thanks in advance!

scuzzman · 11-08-2005, 03:02 AM

This is a quick and dirty (very dirty) way of doing it:

Code:

#!/bin/bash
NUMBER=1
while [ $NUMBER lt 251 ]; do #This will do our counting
  while [ `echo $NUMBER | wc -c` lt 5 ]; do #This adds 0's to the beginning of the number until it's 4 characters in length, I hope.
    let NUMBER=0$NUMBER
  done
  wget http://shadow/edata/ed{$NUMBER}.inf
  let NUMBER += 1 #increment
done

#EOF

I think this should work, but to be safe, add 'echo' before the wget statement to see if it gives the right results... I don't have a box on which I can test it right now.

northy_ie · 11-08-2005, 04:07 AM

Thank you very much for your fast reply!
When I tried to execute the script, I got an "lt: binary operator expected" error in line 3, so I changed the lt to -lt.
I then got an error in line 8. After a google search, I added the quotation marks, that works fine as well now

When running the script now, I get following output:
./backup: line 4: [: +lt: binary operator expected
wget h**p://shadow/edata/ed{241}.inf <- (it's counting up from 1 to 250 okay, seems like the {} are not needed).
But when I change the lt in line4 to -lt, nothing happens, the script just hangs...

Getting very close

this is the current script:

Code:

#!/bin/bash
NUMBER=1
while [ $NUMBER -lt 251 ]; do #This will do our counting
  while [ `echo $NUMBER | wc -c` lt 5 ]; do #This adds 0's to the beginning of the number until it's 4 characters in length, I hope.
    let NUMBER=0$NUMBER
  done
  echo wget h**p://shadow/edata/ed{$NUMBER}.inf
  let "NUMBER += 1" #increment
done

#EOF

scuzzman · 11-08-2005, 06:23 AM

Did you try adding 'echo' to test the output? If not, try that...
I'm not exactly sure what is wrong without seeing the error messages.

northy_ie · 11-08-2005, 06:58 AM

Yes, the script is exactly as in the last post.
When running it, it shows

./backup: line 4: [: lt: binary operator expected
wget h**p://shadow/edata/ed{241}.inf
./backup: line 4: [: lt: binary operator expected
wget h**p://shadow/edata/ed{242}.inf
./backup: line 4: [: lt: binary operator expected
wget h**p://shadow/edata/ed{243}.inf
./backup: line 4: [: lt: binary operator expected
wget h**p://shadow/edata/ed{244}.inf
./backup: line 4: [: lt: binary operator expected
wget h**p://shadow/edata/ed{245}.inf

etc.

destuxor · 11-08-2005, 10:18 AM

I did something identical to what you're asking for to download webcomics this summer, only using Perl.

Code:

#!/usr/bin/perl -w
$x = 1;
while ($x < 365) {
	system ("wget http://hackles.org/strips/cartoon$x.png");
	$x++;
}

To get those leading zeros, I'd use sprintf in a C or Perl script like this (this is a C program):

Code:

#include <stdio.h>
#include <stdlib.h>

int main() {
        char * my_string = calloc(13, sizeof(char));
        int x = 0;
        while (x < 100) {
                sprintf(my_string, "%5d\n", x);
                char * current_char = my_string;
                while (* current_char == ' ') {
                        * current_char = '0';
                        current_char++;
                }
                printf(my_string);
                free(my_string);
                my_string = calloc(13, sizeof(char));
                x++;
        }
        free(my_string);
        return EXIT_SUCCESS;
}

Now you could use this code to write a program to do what you're asking for like this:

Code:

#include <stdio.h>
#include <stdlib.h>

const char * url = "h**p://shadow/edata/ed";

int main() {
        char * my_string = calloc(5, sizeof(char));
        char * my_command = calloc(512+1, sizeof(char));
        int x = 1;
        while (x < 251) {
                sprintf(my_string, "%4d", x);
                char * current_char = my_string;
                while (* current_char == ' ') {
                        * current_char = '0';
                        current_char++;
                }
                sprintf(my_command, "wget %s%s.inf", url, my_string);
                printf("%s\n", my_command);
                // replace the above line with: system("my_command");
                free(my_command);
                my_command = calloc(512+1, sizeof(char));
                free(my_string);
                my_string = calloc(13, sizeof(char));
                x++;
        }
        free(my_string);
        free(my_command);
        return EXIT_SUCCESS;
}

And that should take care of it

chrism01 · 11-09-2005, 12:34 AM

Incidentally, in the bash version, you've only converted the 1st instance of 'lt' => '-lt'. you need to do the same to the 2nd instance, which funnily enough is line 4 (!) as per the error msg...

northy_ie · 11-09-2005, 08:17 AM

Hey again

I did not see the posts from yesterday, so I sat down with a friend of mine and analyzed the script, and we got it working

if anyone is interested, here it is:

Code:

#!/bin/bash
NUMBER=1
while [ $NUMBER -lt 251 ]; do #This will do our counting
COUNTER=$NUMBER
  while [ `echo $COUNTER | wc -c` -lt 5 ]; do #This adds 0's to the beginning of the number until it's 4 characters in length, I hope.
export COUNTER="0"$COUNTER
  done
wget http://shadow/edata/ed$NUMBER.inf
  let "NUMBER += 1" #increment
done

#EOF

Thank you all very much for your help