ubuntu@ubuntu:~$ ls
Desktop    Downloads  img-tools_0.zip  Pictures  Templates
Documents  img-tools  Music            Public    Videos
ubuntu@ubuntu:~$ cd img-tools/
ubuntu@ubuntu:~/img-tools$ ls
ext4fixup  make_ext4fs      mkuserimg.sh  simg_dump.py     unyaffs
img2simg   mkfs.yaffs2.x86  simg2img      system.img.ext4
ubuntu@ubuntu:~/img-tools$ mkdir sys
ubuntu@ubuntu:~/img-tools$ ./simg2img system.img sys.raw
bash: ./simg2img: No such file or directory
ubuntu@ubuntu:~/img-tools$ ls
ext4fixup  make_ext4fs      mkuserimg.sh  simg_dump.py  system.img
img2simg   mkfs.yaffs2.x86  simg2img      sys           unyaffs
ubuntu@ubuntu:~/img-tools$ ./simg2img system.img sys.raw
bash: ./simg2img: No such file or directory
ubuntu@ubuntu:~/img-tools$ chmod +x simg2img 
ubuntu@ubuntu:~/img-tools$ ./simg2img system.img sys.raw
bash: ./simg2img: No such file or directory
ubuntu@ubuntu:~/img-tools$