lua, 86 bytes

Result

AC

Duration

615ms

Code [DL]

d=io.read
f=d(51)h=d'*a'p,c=h:gsub(' *\n','')print(f:rep(c)..p..f.rep(0,f:find"T"-#p))

stdin

                                             T    
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                         K        

stdout

                                             T    
                                             T    
                                             T    
                                             T    
                                             T    
                                             T    
                                             T    
                                             T    
                                             T    
                                         K0000

stderr

strace

11    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7ffdf66c7820 /* 7 vars */) = 0
12    execve("/bin/cat", ["cat", "-"], 0x55ed181a2d30 /* 7 vars */) = 0
12    +++ exited with 0 +++
11    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=12, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
13    execve("/usr/bin/lua5.3", ["/usr/bin/lua5.3", "/volume/CODE"], 0x55ed181a2d40 /* 7 vars */) = 0
13    +++ exited with 0 +++
11    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=13, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
11    +++ exited with 0 +++