运行 apt-get 时，我得到以下输出：
apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
2 not fully installed or removed.
After this operation, 0B of additional disk space will be used.
Do you want to continue [Y/n]?
Setting up linux-image-2.6.32-31-server (2.6.32-31.61) ...
Running depmod.
update-initramfs: Generating /boot/initrd.img-2.6.32-31-server
gzip: stdout: No space left on device
update-initramfs: failed for /boot/initrd.img-2.6.32-31-server
Failed to create initrd image.
dpkg: error processing …我的 debian 机器上的 apt 有问题。自 7 月初以来，我一直无法更新软件包，显然是因为某些密钥已过期。我找到了几个试图帮助我的网站，但提供的解决方案都没有奏效。所以我在这里问。
当我运行“apt-get update”时，出现此错误：
# apt-get update
Get:1 ftp://85.17.159.15 etch Release.gpg [1032B]
Get:2 http://security.debian.org etch/updates Release.gpg [835B]
Hit ftp://85.17.159.15 etch Release
Hit http://security.debian.org etch/updates Release
Err ftp://85.17.159.15 etch Release
Err http://security.debian.org etch/updates Release
[...]
Fetched 107kB in 0s (407kB/s)
Reading package lists... Done
W: GPG error: ftp://85.17.159.15 etch Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 9AA38DCD55BE302B
W: GPG error: http://security.debian.org etch/updates Release: The following signatures couldn't be …