No such file or directory when file exists

Question

I have a file called bitcoind in /usr/bin/bitcoind:

bitcoin@Titan:~$ ll /usr/bin | grep bitcoind
-rwxr-xr-x  1 bitcoin bitcoin 7789600 Nov 25 10:39 bitcoind*

However, I cannot execute it:

bitcoin@Titan:~$ bitcoind
-bash: /usr/bin/bitcoind: No such file or directory

sudo doesn't help:

bitcoin@Titan:~$ sudo bitcoind
sudo: unable to execute /usr/bin/bitcoind: No such file or directory

Found the suggestion that it's because it's missing some required libraries, so tried using 'ldd' to find them:

bitcoin@Titan:~$ ldd /usr/bin/bitcoin
ldd: /usr/bin/bitcoin: No such file or directory

Answer 1

You try to run a 32-bit executable in a 64-bit system. That's not a problem, but you need some packages on your system to be able to do that.

Add the 32-bit architecture to the package library:

sudo dpkg --add-architecture i386

Update the package cache:

sudo apt-get update

And install the needed packages:

sudo apt-get install libc6:i386 libstdc++6:i386 libncurses5:i386 

After that you should be able to execute the 32 bit executable.

A bit of background:

ldd returns not a dynamic executable because it is not a 64 bit executable, hence not a 64 bit dynamic executable. To execute a 64 bit shaed object such as your executable, there must be a dynamic linker: the linux loader. Normally it resides in /lib. In 64-bit linux systems with a 32 bit linker there are two linker/loader: The 32-bit loader in /lib32/ld-linux.so and the 64-bit loader in /lib64/ld-linux.so. A 32-bit executable need 32-bit libraries, so your executable may need some more libraries. Install them in debian based systems with apt-get install libxyz:i386.