QtCreator custom build step problem

[gusa]

Hello.
I have Qt project in QtCreator on Ubuntu. I need to copy some files into build subdirectory after building my project, so I added some custom steps that create subdirectory and move files in it. The problem is that step with mkdir command fails if directory i'm creating already exists. I have not figured out how to do multiple shell commands in one custom step, so i decided to put them all in one shell script. But custom step, that tries to run my shell script gives an error: ******"Can't run process «/home/gusa/Programming/P-Art_Repos/master/UpdatingSystem/PostBuild.sh»"******. I tested my script outside of QtCreator and it works just fine. Can anybody tell me why QtCreator can't run my shell script as custom step?
PostBuild.sh code:

[ -d "mongo-cxx" ] && rm -rf "mongo-cxx"
mkdir "mongo-cxx"
cp -f ../../LIBRARIES/mongo-cxx/Linux/lib/*.so mongo-cxx/

cp -f ../../LIBRARIES/mongo-cxx/Linux/bin/mongo UpdateServer/mongo.exe
cp -f ../../LIBRARIES/mongo-cxx/Linux/bin/mongod UpdateServer/mongod.exe
cp -f ../../LIBRARIES/mongo-cxx/Linux/bin/mongoexport UpdateServer/mongoexport.exe
cp -f ../../LIBRARIES/mongo-cxx/Linux/bin/mongoimport UpdateServer/mongoimport.exe