ruby, 79 bytes

Result

AC

Duration

1174ms

Code [DL]

s=`dd`;puts s.gsub(/^ {#{s[/^ *K/].size-1}}\K /,?#).sub(/# *(?=T)/){?#*$&.size}

stdin

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stdout

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                 K                                

stderr

3+1 records in
3+1 records out

strace

10    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7ffcd113eaa0 /* 9 vars */) = 0
12    execve("/usr/local/ruby-2.6.3/bin/ruby", ["/usr/local/ruby-2.6.3/bin/ruby", "/volume/CODE"], 0x55aa066e6d60 /* 9 vars */) = 0
11    execve("/bin/cat", ["cat", "-"], 0x55aa066e6d40 /* 9 vars */) = 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} ---
13    execve("/bin/dd", ["dd"], 0x56009e9ff300 /* 9 vars */) = 0
13    +++ exited with 0 +++
12    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=13, 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=6, si_stime=4} ---
10    +++ exited with 0 +++