/usr/bin/expect_autopasswd is in expect 5.45-6.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | #!/bin/sh
# -*- tcl -*-
# The next line is executed by /bin/sh, but not tcl \
exec tclsh8.6 "$0" ${1+"$@"}
package require Expect
# wrapper to make passwd(1) be non-interactive
# username is passed as 1st arg, passwd as 2nd
set password [lindex $argv 1]
spawn passwd [lindex $argv 0]
expect "assword:"
send -- "$password\r"
expect "assword:"
send -- "$password\r"
expect eof
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