daria@samsung-laptop:~$ rvm install ruby-2.1.5
Searching for binary rubies, this might take some time.
Found remote file https://rvm_io.global.ssl.fastly.net/binaries/ubuntu/14.04/x86_64/ruby-2.1.5.tar.bz2
Checking requirements for ubuntu.
Installing requirements for ubuntu.
Updating system...................
Error running 'requirements_debian_update_system ruby-2.1.5',
showing last 15 lines of /home/daria/.rvm/log/1422379934_ruby-2.1.5/update_system.log
++ case "${TERM:-dumb}" in
++ case "$1" in
++ [[ -t 2 ]]
++ return 1
++ printf %b 'There has been error while updating '\''apt-get'\'', please give it some time and try again later.
404 errors should be fixed for rvm to proceed. Check your sources configured in:
    /etc/apt/sources.list
    /etc/apt/sources.list.d/*.list
\n'
There has been error while updating 'apt-get', please give it some time and try again later.
404 errors should be fixed for rvm to proceed. Check your sources configured in:
    /etc/apt/sources.list
    /etc/apt/sources.list.d/*.list

++ return 100
Requirements installation failed with status: 100.