我全新安装了 Ubuntu Server 11.10，我正在通过 PuTTy 登录到 SSH。当我在屏幕内时，我无法使用向上箭头来调用 bash 历史记录（尽管这在屏幕外有效）。我似乎无法在 Internet 上找到完全相同的问题（尽管有很多类似的问题）。我的 .screenrc 如下：
# Look and feel
caption always "%{= bb}%{+b w}Screen: %n | %h %=%t %c"
hardstatus alwayslastline "%-Lw%{= BW}%50>%n%f* %t%{-}%+Lw%<"
# Our warning of activity
activity "Activity in %t(%n)"
# Left Right meta key mods
#ALT-,. and ALT-<>
bindkey "^[<" eval number !echo $WINDOW-1|bc
bindkey "^[>" eval number !echo $WINDOW+1|bc
bindkey "^[," prev
bindkey "^[." next
#disable startup banner
startup_message off
#see http://www4.informatik.uni-erlangen.de/~jnweiger/screen-faq.html
termcap xterm 'XT:AF=\E[3%dm:AB=\E[4%dm:AX'
terminfo xterm …在 EC2 中运行的 Ubuntu 13.04 上，sudo除了ls. 以下是一些示例命令来说明问题：
ubuntu at host in ~
$ sudo ls
sudo: command: command not found
ubuntu at host in ~
1 $ sudo which ls
/bin/ls
ubuntu at host in ~
$ sudo /bin/ls
bin dotfiles init npm tmp
ubuntu at host in ~
$ sudo pwd
/home/ubuntu
ubuntu at host in ~
$ sudo which pwd
/bin/pwd
ubuntu at host in ~
$ echo wtf
wtf