The post was deplaced from bug report forum, why? :
First, please make a new post when you have a particular problem instead of posting on existing one which do not concern the same problem.
Second, this is not a bug here but a misunderstanding from your part. So posting on bug report is not a good idea. A problem can be considered as bug when the trouble can be reproducible on the same way on every machine, not the case here.
Third, as it said on the obarun home page site, Obarun is not designed with beginners to Linux in mind, that's mean : if a beginners in linux want use it , he must learn the base of linux command, he must learn how to use console, he must learn how to work pacman, he must learn how to maintain its own system, he must make its own research and understand a command before using it and so one...
So, you can find help here but applying a command without searching what the command mean and how it works is a very bad idea and that is right for every system you use, not in particular on obarun.
Well, try the given command by bit one by one:
mkdir -p tmp/build-octopi
then
cd tmp/build-octopi
yaourt -G octopi
and now, what happen on the directory tmp/build-octopi?
ls
obarun@ obarunS6 build-octopi % ls
octopi/
so as you can see yaourt maded a new folder containing all the necessary to build octopi, you need to place you on the new folder.
cd octopi
now (a very good idea here is to read the man page of makepkg, to know exactly what you made with the bit command, or mine)
makepkg -src
==> Quitte l’environnement fakeroot.
==> Création finie : octopi 0.8.3-1 (dim. août 28 08:27:23 RET 2016)
==> Nettoyage...
obarun@ obarunS6 octopi %
obarun@ obarunS6 octopi % ls -la
total 2,6M
drwxr-xr-x 2 obarun users 4,0K 28 août 08:27 ./
drwxr-xr-x 3 obarun users 4,0K 28 août 08:21 ../
-rw-r--r-- 1 obarun users 2,7K 19 août 16:51 .SRCINFO
-rw-r--r-- 1 obarun users 8,0K 19 août 16:51 PKGBUILD
-rw-r--r-- 1 obarun users 532 19 août 16:51 enable-kstatus.patch
-rw-r--r-- 1 obarun users 465K 28 août 08:27 octopi-0.8.3-1-x86_64.pkg.tar.xz
-rw-r--r-- 1 obarun users 287 28 août 08:27 octopi-0.8.3-1-x86_64.pkg.tar.xz.sig
-rw-r--r-- 1 obarun users 901K 28 août 08:25 octopi-0.8.3-1.tar.gz
-rw-r--r-- 1 obarun users 131K 28 août 08:27 octopi-cachecleaner-0.8.3-1-x86_64.pkg.tar.xz
-rw-r--r-- 1 obarun users 287 28 août 08:27 octopi-cachecleaner-0.8.3-1-x86_64.pkg.tar.xz.sig
-rw-r--r-- 1 obarun users 326K 28 août 08:27 octopi-notifier-frameworks-0.8.3-1-x86_64.pkg.tar.xz
-rw-r--r-- 1 obarun users 287 28 août 08:27 octopi-notifier-frameworks-0.8.3-1-x86_64.pkg.tar.xz.sig
-rw-r--r-- 1 obarun users 321K 28 août 08:27 octopi-notifier-qt4-0.8.3-1-x86_64.pkg.tar.xz
-rw-r--r-- 1 obarun users 287 28 août 08:27 octopi-notifier-qt4-0.8.3-1-x86_64.pkg.tar.xz.sig
-rw-r--r-- 1 obarun users 324K 28 août 08:27 octopi-notifier-qt5-0.8.3-1-x86_64.pkg.tar.xz
-rw-r--r-- 1 obarun users 287 28 août 08:27 octopi-notifier-qt5-0.8.3-1-x86_64.pkg.tar.xz.sig
-rw-r--r-- 1 obarun users 19K 28 août 08:27 octopi-pacmanhelper-0.8.3-1-x86_64.pkg.tar.xz
-rw-r--r-- 1 obarun users 287 28 août 08:27 octopi-pacmanhelper-0.8.3-1-x86_64.pkg.tar.xz.sig
-rw-r--r-- 1 obarun users 81K 28 août 08:27 octopi-repoeditor-0.8.3-1-x86_64.pkg.tar.xz
-rw-r--r-- 1 obarun users 287 28 août 08:27 octopi-repoeditor-0.8.3-1-x86_64.pkg.tar.xz.sig
-rw-r--r-- 1 obarun users 198 19 août 16:51 octopi-repoeditor.desktop
now you can install the desired package with pacman -U command (same thing here, man pacman) :
sudo pacman -U name_of_the_package
So as you can see your trouble is very easy to solve and do not need to ask some help if you think a minimum
