為什麼找不到 sendmail？

我剛剛在 Debian 上安裝了 Postfix，並在我的 VPS 上遵循本指南。

當我執行命令時： $ echo "test email" | sendmail your-account@gmail.com

sendmail: command not found

為什麼會這樣？

有人建議我執行以下命令：

$ sudo find / -name "sendmail"
/var/lib/sendmail
/usr/sbin/sendmail
/usr/lib/sm.bin/sendmail
/usr/lib/sendmail
/usr/share/sendmail
/usr/share/sendmail/examples/dhcp/dhclient-exit-hooks.d/sendmail
/usr/share/sendmail/examples/logcheck/ignore.d.paranoid/sendmail
/usr/share/sendmail/examples/logcheck/ignore.d.server/sendmail
/usr/share/sendmail/examples/logcheck/ignore.d.workstation/sendmail
/usr/share/sendmail/examples/network/if-down.d/sendmail
/usr/share/sendmail/examples/network/if-post-down.d/sendmail
/usr/share/sendmail/examples/network/if-up.d/sendmail
/usr/share/sendmail/examples/ppp/ip-down.d/sendmail
/usr/share/sendmail/examples/ppp/ip-up.d/sendmail
/usr/share/sendmail/examples/resolvconf/update-libc.d/sendmail
/usr/share/sendmail/sendmail
/etc/logcheck/ignore.d.server/sendmail
/etc/logcheck/ignore.d.paranoid/sendmail
/etc/logcheck/ignore.d.workstation/sendmail
/etc/cron.d/sendmail
/etc/network/if-down.d/sendmail
/etc/network/if-post-down.d/sendmail
/etc/network/if-up.d/sendmail
/etc/dhcp/dhclient-exit-hooks.d/sendmail
/etc/alternatives/sendmail
/etc/init.d/sendmail
/etc/cron.daily/sendmail
/etc/ppp/ip-up.d/sendmail
/etc/ppp/ip-down.d/sendmail
/etc/resolvconf/update-libc.d/sendmail
/run/sendmail

/usr/sbin 通常不在使用者的 PATH 上，只在 root 的路徑上。

引用自：https://serverfault.com/questions/1060988