Now I’ve solved the problem asked in Unable to build Elixir with Erlang OTP 21: 'cannot get bootfile','no_dot_erlang.boot' and was able to successfully build and run Elixir v1.6.6 on OTP21. I then installed the binaries to usr/local/bin with make install. However, I encountered the following problem when I try to run elixir or mix with sudo:

{"init terminating in do_boot",{undef,[{elixir,start_cli,[],[]},{init,start_em,1,[]},{init,do_boot,3,[]}]}}
init terminating in do_boot ({undef,[{elixir,start_cli,[],[]},{init,start_em,1,[]},{init,do_boot,3,[]}]})

Searching related problems indicated that this is normally caused by the version mismatch between the Erlang used to build the Elixir and the current Erlang installed. However that doesn’t seem to be the case as I’m able to run those commands without root totally fine.

I wonder if there’s something in my environment variables that is not in root's, but I don’t think so.

Also, if I try to run sudo iex, I get

2018-06-25 22:43:14.264462 crash_report        #{label=>{proc_lib,crash},report=>[[{initial_call,{supervisor_bridge,user_sup,['Argument__1']}},{pid,<0.60.0>},{registered_name,[]},{error_info,{error,undef,[{'Elixir.IEx.CLI',start,[],[]},{user_sup,start_user,3,[{file,"user_sup.erl"},{line,100}]},{user_sup,init,1,[{file,"user_sup.erl"},{line,49}]},{supervisor_bridge,init,1,[{file,"supervisor_bridge.erl"},{line,82}]},{gen_server,init_it,2,[{file,"gen_server.erl"},{line,374}]},{gen_server,init_it,6,[{file,"gen_server.erl"},{line,342}]},{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,249}]}]}},{ancestors,[kernel_sup,<0.45.0>]},{message_queue_len,0},{messages,[]},{links,[<0.47.0>]},{dictionary,[]},{trap_exit,true},{status,running},{heap_size,610},{stack_size,27},{reductions,274}],[]]}
2018-06-25 22:43:14.264511 supervisor_report   #{label=>{supervisor,start_error},report=>[{supervisor,{local,kernel_sup}},{errorContext,start_error},{reason,{undef,[{'Elixir.IEx.CLI',start,[],[]},{user_sup,start_user,3,[{file,"user_sup.erl"},{line,100}]},{user_sup,init,1,[{file,"user_sup.erl"},{line,49}]},{supervisor_bridge,init,1,[{file,"supervisor_bridge.erl"},{line,82}]},{gen_server,init_it,2,[{file,"gen_server.erl"},{line,374}]},{gen_server,init_it,6,[{file,"gen_server.erl"},{line,342}]},{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,249}]}]}},{offender,[{pid,undefined},{id,user},{mfargs,{user_sup,start,[]}},{restart_type,temporary},{shutdown,2000},{child_type,supervisor}]}]}
2018-06-25 22:43:14.266282 crash_report        #{label=>{proc_lib,crash},report=>[[{initial_call,{application_master,init,['Argument__1','Argument__2','Argument__3','Argument__4']}},{pid,<0.44.0>},{registered_name,[]},{error_info,{exit,{{shutdown,{failed_to_start_child,user,{undef,[{'Elixir.IEx.CLI',start,[],[]},{user_sup,start_user,3,[{file,"user_sup.erl"},{line,100}]},{user_sup,init,1,[{file,"user_sup.erl"},{line,49}]},{supervisor_bridge,init,1,[{file,"supervisor_bridge.erl"},{line,82}]},{gen_server,init_it,2,[{file,"gen_server.erl"},{line,374}]},{gen_server,init_it,6,[{file,"gen_server.erl"},{line,342}]},{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,249}]}]}}},{kernel,start,[normal,[]]}},[{application_master,init,4,[{file,"application_master.erl"},{line,138}]},{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,249}]}]}},{ancestors,[<0.43.0>]},{message_queue_len,1},{messages,[{'EXIT',<0.45.0>,normal}]},{links,[<0.43.0>,<0.42.0>]},{dictionary,[]},{trap_exit,true},{status,running},{heap_size,987},{stack_size,27},{reductions,184}],[]]}
2018-06-25 22:43:14.267451 std_info            #{label=>{application_controller,exit},report=>[{application,kernel},{exited,{{shutdown,{failed_to_start_child,user,{undef,[{'Elixir.IEx.CLI',start,[],[]},{user_sup,start_user,3,[{file,"user_sup.erl"},{line,100}]},{user_sup,init,1,[{file,"user_sup.erl"},{line,49}]},{supervisor_bridge,init,1,[{file,"supervisor_bridge.erl"},{line,82}]},{gen_server,init_it,2,[{file,"gen_server.erl"},{line,374}]},{gen_server,init_it,6,[{file,"gen_server.erl"},{line,342}]},{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,249}]}]}}},{kernel,start,[normal,[]]}}},{type,permanent}]}
{"Kernel pid terminated",application_controller,"{application_start_failure,kernel,{{shutdown,{failed_to_start_child,user,{undef,[{'Elixir.IEx.CLI',start,[],[]},{user_sup,start_user,3,[{file,\"user_sup.erl\"},{line,100}]},{user_sup,init,1,[{file,\"user_sup.erl\"},{line,49}]},{supervisor_bridge,init,1,[{file,\"supervisor_bridge.erl\"},{line,82}]},{gen_server,init_it,2,[{file,\"gen_server.erl\"},{line,374}]},{gen_server,init_it,6,[{file,\"gen_server.erl\"},{line,342}]},{proc_lib,init_p_do_apply,3,[{file,\"proc_lib.erl\"},{line,249}]}]}}},{kernel,start,[normal,[]]}}}"}
Kernel pid terminated (application_controller) ({application_start_failure,kernel,{{shutdown,{failed_to_start_child,user,{undef,[{'Elixir.IEx.CLI',start,[],[]},{user_sup,start_user,3,[{file,"user_sup.

I understand that a more formal deployment procedure would involve some sort of proxy such as Nginx or HAProxy sitting at the HTTP/HTTPS ports while the Elixir app itself runs on a port above 1024. However I just wanted to test whether the app works as I expected first by trying to put it on port 80. It seems to be difficult to do so without running elixir as root. I’m not sure if this is a good idea at all though. I’m mostly curious why the programs don’t work with sudo.

System: Kernel: 3.10.0-693.21.1.el7.x86_64 x86_64 bits: 64 gcc: 4.8.5
           Console: tty 0 Distro: Scientific Linux release 7.5 (Nitrogen)

Erlang/OTP 21 [erts-10.0] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:1] [hipe]

Elixir 1.6.6 (compiled with OTP 21)