Bash : Copy a file every one minute

macabre_sunsets · 09-12-2006, 11:05 PM

Hello
I would like some help in making a bash script for copying a file every one minute
from one location to another. I would like the "target" file to have a different
name from the "source" by adding a digit (which increases) in the end of it.

For example I have a file "test.txt"
The first minute it will be "test_01.txt"
The second minute "test_02.txt" and so on

I thought (since I know nothing about bash scripting) to write to a third file the
number (01, 02, ...), then read it and append it to the "target" file.
Is this possible? Is there an easier way? I have some experience in C. Can I use C
to achieve this?

Thanks in advance

BiThian · 09-12-2006, 11:12 PM

Well, I'ld suggest you using date, sleep or, why not, crontab

macabre_sunsets · 09-12-2006, 11:15 PM

I am planning to create the bash script and the "call" it every minute by crontab.
But I want to rename the new file. How is that possible?

BiThian · 09-12-2006, 11:20 PM

cp? (10 chars

)

debulu · 09-12-2006, 11:22 PM

A effective solution for this will be creating a deamon by using C program which will sleep for say 1 minute and resume its operation and create the new file name (by setting a counter this can be easily achived) and then copy it to the destination. fork/exec pair can achive all these. Refer Advanced Unix programming by R.Stevens for creation of deamon.

macabre_sunsets · 09-12-2006, 11:40 PM

I don't know and I don't want to create a daemon.
Isn't it easier to read the number from the file, append it to the filename,
increase it by one and write it back to the file? Crontab can easily run the script
every minute.
Maybe perl can make things easier?

ghostdog74 · 09-12-2006, 11:41 PM

Quote:

Originally Posted by macabre_sunsets

Hello
I would like some help in making a bash script for copying a file every one minute
from one location to another. I would like the "target" file to have a different
name from the "source" by adding a digit (which increases) in the end of it.

For example I have a file "test.txt"
The first minute it will be "test_01.txt"
The second minute "test_02.txt" and so on

I thought (since I know nothing about bash scripting) to write to a third file the
number (01, 02, ...), then read it and append it to the "target" file.
Is this possible? Is there an easier way? I have some experience in C. Can I use C
to achieve this?

Thanks in advance

An alternative, in Python:

Code:

import os,time,shutil
counter = 1
filename = "test.txt"
dir_of_testfile = "/home"
destination = "/destination"
os.chdir(dir_of_testfile)
while True:
	if not os.path.exists(filename):
		continue
	newfile = "%s_%s.txt" %(filename[:-4] , str(counter).zfill(2) ) #eg test_01.txt,test_02.txt
	shutil.move(filename, os.path.join(destination,newfile) )
	counter += 1 #increment counter
	time.sleep(60) #sleep 1 min

macabre_sunsets · 09-12-2006, 11:53 PM

Nice idea!
Unfortunately I don't have python installed (i try 'python script.py' but nothing
happens).
I will give it a try to translate it in bash.
But there is still one problem. I want the file to be copied 24/7. That means that
the number will increase greatly and the loops are going to be longer and longer.
That's why I thought of the seperate file acting as a kind of counter.

chrism01 · 09-13-2006, 12:00 AM

Code:

old="test.txt"
base_name=`basename $old .txt`
old_num=`cat num.txt`
(( old_num += 1 ))
if [[ $old_num -lt 10 ]]
then
    new_num="0"${old_num}
    echo $new_num
else
    new_num=$old_num
    echo $new_num
fi
new=${base_name}"_"${new_num}".txt"
echo $new
cp $old $new
echo $old_num >num.txt

which you could run from cron every minute

macabre_sunsets · 09-13-2006, 12:09 AM

Great job! Thank you a lot!
Can I ask for a small correction?
The numbers now are two-digit (01,02,....,10,20). How can I make them 6-digit?
I changed this 'new_num="0"${old_num}' to 'new_num="0000000"${old_num}' but no more digits were added.
Any idea? I just want more digits so when I sort the images to be in the right order.

macabre_sunsets · 09-13-2006, 12:12 AM

My mistake

It works just fine with the 6 zeroes

Output :

0000001
webcam_0000001.jpg

Exactly what I wanted. Thanks very very much and everyone else who helped me.

macabre_sunsets · 09-13-2006, 12:21 AM

Quote:

old="/var/www/cam/webcam.jpg"
base_name=`basename $old .jpg`
dire='/home/lugubrious/webcam_photos/'
old_num=`cat /home/lugubrious/webcam_photos/num.txt`
(( old_num += 1 ))
if [[ $old_num -lt 10 ]]
then
new_num="000000"${old_num}
else
new_num=$old_num
fi
new=${dire}${base_name}"_"${new_num}".jpg"
cp $old $new
echo $old_num >num.txt

Here's the complete script in it's final shape.
It reads and writes in a specific directory and has a 6-digit number appended.
Thanks a lot for you instant help.

chrism01 · 09-13-2006, 12:21 AM

You need to add extra tests for -lt 100, -lt 1000 etc up to the number of digits you require.
It's a bit of a hack, but pure shell wasn't really designed (originally) for this sort of thing.
You could prob do a clever num format via something like awk or even sed I'd guess.
Personally, if this prog/daemon is going to do much more (or is really part of something else), I'd do it in Perl.
YMMV
.
.
.
Actually, this works

Code:

old="test.txt"
base_name=`basename $old .txt`
old_num=`cat num.txt`
(( old_num += 1 ))
new_num=`printf "%03d" $old_num`
echo $new_num
new=${base_name}"_"${new_num}".txt"
echo $new
cp $old $new
echo $old_num >num.txt

edit the printf to suit

macabre_sunsets · 09-13-2006, 12:34 AM

No it is not going to do anything else and is not a part of some other program. I just want to capture
images from my webcam and store them. Maybe perl would be better but since it works it is just fine.
What do you mean about the extra test for -lt 100?

chrism01 · 09-13-2006, 01:50 AM

ignore that comment, just use the new code and amend the printf format (man printf) to match the num of digits you require.