[BASH] How to create your own postprocessingscript
Posted: February 9th, 2011, 9:11 am
Bash is a flexible language and not that hard to write. Just open a blank textfile and write a shebang in the first line: #!/bin/bash (or #!/usr/bin/env bash) and commands on the next.
When you want to explain something in the script, or stop a command from executing, put a # in front of it, it disables all text after that line that line specifically.
# Commands
Basically it's just commands you would enter normally in the terminal and write them down in the script.
Sab serves some things to a script so you can use them to execute the commands with, listed here: http://wiki.sabnzbd.org/user-scripts. In Bash you can use these by naming them $1 to $7. Copying a downloaded folder ($1) is easy that way, open a textfile, shebang at top, enter cp $1 /new/location. Save it make it executable, and there you have it, your first postprocessingscript.
# Variables
As above Sabnzbd executes a script and gives it 7 variables ($1 to $7). You can create your own variables too, or rename the variables Sabnzbd passes to the script. Variables are made by word=something (= is used to define a variable) and then callable by using a $ sign for it, like $word.
Some examples:
name=mars ($name) >> output your name in terminal or log >usage: echo "Hi my name is $name"
location=/some/folder/on/my/nas ($location) >> copy a file to that folder on nas > usage: cp $1/*.avi $location
cleannzb=$3 ($cleannzb) >> output that name in terminal or log > usage: echo "$name copied $1 to $location, job $cleannzb is done"
Variables can be a command to, use the command inside $(). actioncopy=$(cp *.avi /home/user/Videos) $actioncopy will execute it.
Using variables makes a script flexible and editable, change a variable and everywhere it's used it will be changed too. Usually they are written before all functions.
# Functions
Using code from someone else is also easy. Just use functions. You can call them whatever you like and write 'm like this:
Make sure you put the functionname (without the '() {') also at the bottom of the script execute the functions. This makes it easy to run just a part of a script (comment functions to disable them) and easy for others to edit the script to specific needs or borrow functions from other scripts.
Now you want to combine two scripts that cleans up your downloadfolder and then copy's it to a specific directory and then tells (echo) you you are a great guy and then start a script someone else wrote. Search this forum for other scripts that do that, for example [url=http://"http://forums.sabnzbd.org/index.php?topic=5031.0"]this[/url] and [url=http://"http://forums.sabnzbd.org/index.php?topic=4748.0"]this[/url] one. Embed them in functions and the new script will be:
# More difficult functions
Bash has many ways to check for conditions. Those are called statements. For example if-statements are most used in script.
If statements condition like "if this then do x else do y fi". A simple example:
As you see if, else and fi are on the left and the things in between a tab (or 4 spaces) to the right. This is for readability, and most of the time not really necessary. Google will help if you need more difficult functions to do something, also see the sources below.
# Running multiple scripts from 1 script
This is also easy. You can do 2 things. First the easiest:
1. Blank textfile, shebang @ top and the following lines in the script:
./path/toscript/one/scriptname1
./path/toscript/two/scriptname2 &&
./and/so/on.
2. Copy all text in all scripts, put the code from script one in function1, script two in function 2 etc. (watch out with variables here by the way).
If you put && after an executescriptcommand the next command will only be started if the previous one was succesful (see example scriptname2).
# Great sources for bashwriting are:
http://mywiki.wooledge.org/EnglishFrontPage
http://www.faqs.org/docs/Linux-HOWTO/Ba ... HOWTO.html
and google of course.
The basic thing is:
If you repeatedly do the same stuff on your linux-pc, over and over again, then write a bashscript for it. Throw all commands you use in a file, shebang at top and functions at bottom and chmod +x it. It will save you a lot of time (after you invest some first) and you will learn a lot about bash and linux. You can make Sabnzbd do fun stuff and make nice logs.
for example a script with:
echo "Hi $name, I did this job called $3 for you, as you feeded me $2, I moved it to $1 for you, hope you will enjoy this $5."
(You can log this into a real file with > /home/user/filename.txt at the end).
Have fun scripting! ;)
Forgot one thing:
It's always a good idea to use #/bin/bash -x as a shebang when writing scripts from scratch. This will enter debugmode and the output in terminal will be much more verbose, so it will be easier to find mistakes.
When you want to explain something in the script, or stop a command from executing, put a # in front of it, it disables all text after that line that line specifically.
# Commands
Basically it's just commands you would enter normally in the terminal and write them down in the script.
Sab serves some things to a script so you can use them to execute the commands with, listed here: http://wiki.sabnzbd.org/user-scripts. In Bash you can use these by naming them $1 to $7. Copying a downloaded folder ($1) is easy that way, open a textfile, shebang at top, enter cp $1 /new/location. Save it make it executable, and there you have it, your first postprocessingscript.
# Variables
As above Sabnzbd executes a script and gives it 7 variables ($1 to $7). You can create your own variables too, or rename the variables Sabnzbd passes to the script. Variables are made by word=something (= is used to define a variable) and then callable by using a $ sign for it, like $word.
Some examples:
name=mars ($name) >> output your name in terminal or log >usage: echo "Hi my name is $name"
location=/some/folder/on/my/nas ($location) >> copy a file to that folder on nas > usage: cp $1/*.avi $location
cleannzb=$3 ($cleannzb) >> output that name in terminal or log > usage: echo "$name copied $1 to $location, job $cleannzb is done"
Variables can be a command to, use the command inside $(). actioncopy=$(cp *.avi /home/user/Videos) $actioncopy will execute it.
Using variables makes a script flexible and editable, change a variable and everywhere it's used it will be changed too. Usually they are written before all functions.
# Functions
Using code from someone else is also easy. Just use functions. You can call them whatever you like and write 'm like this:
Code: Select all
nameoffunction () {
commands you want to execute
}
Now you want to combine two scripts that cleans up your downloadfolder and then copy's it to a specific directory and then tells (echo) you you are a great guy and then start a script someone else wrote. Search this forum for other scripts that do that, for example [url=http://"http://forums.sabnzbd.org/index.php?topic=5031.0"]this[/url] and [url=http://"http://forums.sabnzbd.org/index.php?topic=4748.0"]this[/url] one. Embed them in functions and the new script will be:
Code: Select all
!/bin/bash
#### clean up directory so execute cleanupscript
topic1 () {
GARBAGE=".nfo .srr .sfv .nzb .jpg" #### Add or remove extensions here
for junk in $GARBAGE
do
find $1 -name *$junk -type f -exec rm -f {} \;
done
}
#### the above function does the same as the more readable:
removefiles () {
rm -f $1/*.nfo
rm -f $1/*.srr
rm -f $1/*.sfv
rm -f $1/*.nzb
rm -f $1/*.jpg
}
#### copy to someplace if movies and another if tvshows copied from forum and embedded in function
topic2 () {
if [ "$5" = "movies" ]; then
mv -fv "$1" "/Volumes/External HD/Media/Movies"
elif [ "$5" = "tv" ]; then
mv -fv "$1" "/Volumes/External HD/Media/TV"
fi
}
#### Yes I wrote my own bashscript
tellme () {
echo "I love Linux and Sabnzbd!"
}
#### execute all the above function, except the first
#topic1 #because this one is commented it won't execute.
removefiles # you can test one function of your script by commenting all the other functions and then run the script.
topic2
tellme# More difficult functions
Bash has many ways to check for conditions. Those are called statements. For example if-statements are most used in script.
If statements condition like "if this then do x else do y fi". A simple example:
Code: Select all
if $name=mars
then
echo "hi $name" #this can be a command too, or multiple commands like this
rm -f /home/mars/*.rar
echo "Oh noes, I accidentally 98mb of rar-files, is that bad?
else
echo "hi i don't know your name"
fi# Running multiple scripts from 1 script
This is also easy. You can do 2 things. First the easiest:
1. Blank textfile, shebang @ top and the following lines in the script:
./path/toscript/one/scriptname1
./path/toscript/two/scriptname2 &&
./and/so/on.
2. Copy all text in all scripts, put the code from script one in function1, script two in function 2 etc. (watch out with variables here by the way).
If you put && after an executescriptcommand the next command will only be started if the previous one was succesful (see example scriptname2).
# Great sources for bashwriting are:
http://mywiki.wooledge.org/EnglishFrontPage
http://www.faqs.org/docs/Linux-HOWTO/Ba ... HOWTO.html
and google of course.
The basic thing is:
If you repeatedly do the same stuff on your linux-pc, over and over again, then write a bashscript for it. Throw all commands you use in a file, shebang at top and functions at bottom and chmod +x it. It will save you a lot of time (after you invest some first) and you will learn a lot about bash and linux. You can make Sabnzbd do fun stuff and make nice logs.
for example a script with:
echo "Hi $name, I did this job called $3 for you, as you feeded me $2, I moved it to $1 for you, hope you will enjoy this $5."
(You can log this into a real file with > /home/user/filename.txt at the end).
Have fun scripting! ;)
Forgot one thing:
It's always a good idea to use #/bin/bash -x as a shebang when writing scripts from scratch. This will enter debugmode and the output in terminal will be much more verbose, so it will be easier to find mistakes.
Thanks for the help though with the quotes!