Executing a Bash Script Upon File Creation

Executing a bash script upon file creation

How about incron? It triggering Commands On File/Directory Changes.

sudo apt-get install incron

Example:

<path> <mask> <command>

Where <path> can be a directory (meaning the directory and/or the files directly in that directory (not files in subdirectories of that directory!) are watched) or a file.

<mask> can be one of the following:

IN_ACCESS           File was accessed (read) (*)
IN_ATTRIB           Metadata changed (permissions, timestamps, extended attributes, etc.) (*)
IN_CLOSE_WRITE      File opened for writing was closed (*)
IN_CLOSE_NOWRITE    File not opened for writing was closed (*)
IN_CREATE           File/directory created in watched directory (*)
IN_DELETE           File/directory deleted from watched directory (*)
IN_DELETE_SELF           Watched file/directory was itself deleted
IN_MODIFY           File was modified (*)
IN_MOVE_SELF        Watched file/directory was itself moved
IN_MOVED_FROM       File moved out of watched directory (*)
IN_MOVED_TO         File moved into watched directory (*)
IN_OPEN             File was opened (*)

<command> is the command that should be run when the event occurs. The following wildards may be used inside the command specification:

$$   dollar sign
$@   watched filesystem path (see above)
$#   event-related file name
$%   event flags (textually)
$&   event flags (numerically)

If you watch a directory, then $@ holds the directory path and $# the file that triggered the event. If you watch a file, then $@ holds the complete path to the file and $# is empty.

Working Example:

$sudo echo spatel > /etc/incron.allow
$sudo echo root > /etc/incron.allow

Start Daemon:

$sudo /etc/init.d/incrond start

Edit incrontab file

$incrontab -e
/home/spatel IN_CLOSE_WRITE touch /tmp/incrontest-$#

Test it

$touch /home/spatel/alpha

Result:

$ls -l /tmp/*alpha*
-rw-r--r-- 1 spatel spatel 0 Feb  4 12:32 /tmp/incrontest-alpha

Notes: In Ubuntu you need to activate inotify at boot time. Please add following line in Grub menu.lst file:

kernel /boot/vmlinuz-2.6.26-1-686 root=/dev/sda1 ro inotify=yes

How to create a shell script which can create a .java file on executing?

Here-docs will expand variables, so

NAME=$1
cat << EOF > $NAME.java
class $NAME{
   public static void main(String[] args){
      for(int i=0;i<10;i++){
      System.out.println("Hello World !!!"); 
   }
}
EOF

How to get rid of creation of =0 file while running a shell script?

The error is in while [ $num_dir>=0 ] The condition redirects the "output" of $num_dir to the file =0.

You need

while [ $num_dir -ge 0 ]

Or the Bash-specific

while [[ $num_dir >= 0 ]]

shell script to create multiple files, incrementing from last file upon next execution

Based on my comment above and your description, you can write a script that will create 10 numbered files (by default) each time it is run, starting with the next available number. As mentioned, rather than just use a raw-unpadded number, it's better for general sorting and listing to use zero-padded numbers, e.g. 001, 002, ...

If you just use 1, 2, ... then you end up with odd sorting when you reach each power of 10. Consider the first 12 files numbered 1...12 without padding. a general listing sort would produce:

file1
file11
file12
file2
file3
file4
...

Where 11 and 12 are sorted before 2. Adding leading zeros with printf -v avoids the problem.

Taking that into account, and allowing the user to change the prefix (first part of the file name) by giving it as an argument, and also change the number of new files to create by passing the count as the 2nd argument, you could do something like:

 #!/bin/bash

prefix="${1:-file_}"                ## beginning of filename
number=1                            ## start number to look for
ext="txt"                           ## file extension to add

newcount="${2:-10}"                 ## count of new files to create

printf -v num "%03d" "$number"      ## create 3-digit start number
fname="$prefix$num.$ext"            ## form first filename

while [ -e "$fname" ]; do           ## while filename exists
  number=$((number + 1))            ## increment number
  printf -v num "%03d" "$number"    ## form 3-digit number
  fname="$prefix$num.$ext"          ## form filename
done

while ((newcount--)); do            ## loop newcount times
  touch "$fname"                    ## create filename
  ((! newcount)) && break;          ## newcount 0, break (optional)
  number=$((number + 1))            ## increment number
  printf -v num "%03d" "$number"    ## form 3-digit number
  fname="$prefix$num.$ext"          ## form filename
done

Running the script without arguments will create the first 10 files, file_001.txt - file_010.txt. Run a second time, it would create 10 more files file_011.txt to file_020.txt.

To create a new group of 5 files with the prefix of list_, you would do:

bash scriptname list_ 5

Which would result in the 5 files list_001.txt to list_005.txt. Running again with the same options would create list_006.txt to list_010.txt.

Since the scheme above with 3 digits is limited to 1000 files max (if you include 000), there isn't a big need to get the number from the last file written (bash can count to 1000 quite fast). However, if you used 7-digits, for 10 million files, then you would want to parse the last number with ls -1 | tail -n 1 (or version sort and choose the last file). Something like the following would do:

  number=$(ls -1 "$prefix"* | tail -n 1 | grep -o '[1-9][0-9]*')

(note: that is ls -(one) not ls -(ell))

Let me know if that is what you are looking for.

How to create and run a bash file?

As you have two different OS setup, I will split my answer in two parts.

First: Windows

Windows does not have a Bash interpreter, nor the afconvert program the code above is trying tu run. Your best bet will be to use Cygwin to install a Unix console on your Windows. Also I don't know, where you could get afconvert from.

OSX

OSX does have a console and the afconvert software (at least my OSX does). You can simply drop the file in a folder and give it a name ending in .sh. Then you should be able to run it.

How do I execute a bash script in Terminal?

$prompt: /path/to/script and hit enter. Note you need to make sure the script has execute permissions.

Bash Script to execute linux file

for i in `seq 0 10`
do
 ./bomb filename$i.txt
done

The above code will run from filename0 to filename10

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