standback, 42 bytes

Result

AC

Duration

842ms

Code [DL]

g/[^T]{50}\K./T/w/K /s/K /KK//m//S//%%'///

stdin

                           T                      
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                       K                          

stdout

                           T                      
                           T                      
                           T                      
                           T                      
                           T                      
                           T                      
                           T                      
                           T                      
                           T                      
                           T                      
                           T                      
                           T                      
                       KKKKT                      

stderr

strace

10    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7ffc8ba9c720 /* 9 vars */) = 0
11    execve("/bin/cat", ["cat", "-"], 0x55736da42068 /* 9 vars */ <unfinished ...>
12    execve("/usr/local/ruby-2.6.3/bin/ruby", ["/usr/local/ruby-2.6.3/bin/ruby", "/root/standback/src/standback.rb", "/volume/CODE"], 0x55736da42090 /* 9 vars */ <unfinished ...>
11    <... execve resumed> )            = 0
12    <... execve resumed> )            = 0
11    +++ exited with 0 +++
10    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=11, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
12    +++ exited with 0 +++
10    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=12, si_uid=0, si_status=0, si_utime=7, si_stime=3} ---
10    +++ exited with 0 +++