ssh-addとexpectによるパスフレーズ入力がcronでは機能しない

eval `ssh-agent -s`
expect -d -c '
spawn ssh-add /home/hoge/.ssh/id_dsa
expect "Enter passphrase for"
send "hogehoge\\r"
interact
'

Agent pid 7260
expect version 5.42.1
spawn ssh-add /home/hoge/.ssh/id_dsa
parent: waiting for sync byte
parent: telling child to go ahead
parent: now unsynchronized from child
spawn: returns {7262}

expect: does "" (spawn_id exp4) match glob pattern "Enter passphrase for"? no
Enter passphrase for /home/hoge/.ssh/id_dsa:
expect: does "Enter passphrase for /home/hoge/.ssh/id_dsa: " (spawn_id exp4) match glob pattern "Enter passphrase for"? yes
expect: set expect_out(0,string) "Enter passphrase for"
expect: set expect_out(spawn_id) "exp4"
expect: set expect_out(buffer) "Enter passphrase for"
send: sending "hogehoge\\r" to { exp4 }
tty_raw_noecho: was raw = 0  echo = 1
spawn id exp4 sent <\\r\\n>

spawn id exp4 sent <Identity added: /home/hoge/.ssh/id_dsa (/home/hoge/.ssh/id_dsa)\\r\\n>
Identity added: /home/hoge/.ssh/id_dsa (/home/hoge/.ssh/id_dsa)
interact: received eof from spawn_id exp4

Agent pid 7297
expect version 5.42.1
spawn ssh-add /home/hoge/.ssh/id_dsa
parent: waiting for sync byte
parent: telling child to go ahead
parent: now unsynchronized from child
spawn: returns {7299}

expect: does "" (spawn_id exp3) match glob pattern "Enter passphrase for"? no
Enter passphrase for /home/hoge/.ssh/id_dsa:
expect: does "Enter passphrase for /home/hoge/.ssh/id_dsa: " (spawn_id exp3) match glob pattern "Enter passphrase for"? yes
expect: set expect_out(0,string) "Enter passphrase for"
expect: set expect_out(spawn_id) "exp3"
expect: set expect_out(buffer) "Enter passphrase for"
send: sending "hogehoge\\r" to { exp3 }
interact: received eof from spawn_id exp0