增加旧内核的数量以保持自动删除。

Question

看起来我的Ubuntu 18.04在/boot目录下保留了一个旧的Linux内核（所以我有一个旧内核和一个当前内核）。在运行sudo apt autoremove或full-upgrade时，是否可以增加要保留的旧内核数量，例如我想保留最近的三个旧内核（因此我将有3个旧内核+1个当前内核=4个内核）？将磁盘空间四舍五入到64MB，用于内核和initrd.img x 4 = 256MB，在/boot目录下我有足够的空间可以使用，并且希望保留一些旧内核以确保安全。

在CentOS 6和7中，可以通过编辑/etc/yum.conf并设置installonly_limit=3来实现这一点（默认为5）。

- Neon

Answer 1

很遗憾，没有这样的配置，我们需要编辑负责创建/etc/apt/apt.conf.d/01autoremove-kernels的脚本。

所以我稍微查看了一下脚本，只需进行一些小的更改就可以得到你想要的结果。

首先备份/etc/kernel/postinst.d/apt-auto-removal：

sudo cp /etc/kernel/postinst.d/apt-auto-removal{,.bk}

然后找到这一行：

previous_version="$(echo "$debverlist" | sed -n 2p)"

并将其更改为：

previous_version="$(echo "$debverlist" | sed -n 2,4p)"

现在它应该保留3个旧内核 + 运行中的内核 + 新安装的内核。 当然了，你需要手动运行一次或者安装一个新的内核以使其生效。

---

或者使用我的修改来更改文件，这样您就可以轻松地更改要保留的内核数量：

NKER=1

#!/bin/sh
set -e
# Mark as not-for-autoremoval those kernel packages that are:
#  - the currently booted version
#  - the kernel version we've been called for
#  - the latest kernel version (as determined by debian version number)
#  - the second-latest kernel version
#
# In the common case this results in two kernels saved (booted into the
# second-latest kernel, we install the latest kernel in an upgrade), but
# can save up to four. Kernel refers here to a distinct release, which can
# potentially be installed in multiple flavours counting as one kernel.

# Specify the number of kernels you want to keep
NKER=1
NKER=$((NKER+1))

eval $(apt-config shell APT_CONF_D Dir::Etc::parts/d)
test -n "${APT_CONF_D}" || APT_CONF_D="/etc/apt/apt.conf.d"
config_file="${APT_CONF_D}/01autoremove-kernels"

eval $(apt-config shell DPKG Dir::bin::dpkg/f)
test -n "$DPKG" || DPKG="/usr/bin/dpkg"

list="$("${DPKG}" -l | awk '/^[ih][^nc][ ]+(linux|kfreebsd|gnumach)-image-[0-9]+\./ && $2 !~ /-dbg(:.*)?$/ && $2 !~ /-dbgsym(:.*)?$/ { print $2,$3; }' \
   | sed -e 's#^\(linux\|kfreebsd\|gnumach\)-image-##' -e 's#:[^:]\+ # #')"
debverlist="$(echo "$list" | cut -d' ' -f 2 | sort --unique --reverse --version-sort)"

if [ -n "$1" ]; then
    installed_version="$(echo "$list" | awk "\$1 == \"$1\" { print \$2;exit; }")"
fi
unamer="$(uname -r | tr '[A-Z]' '[a-z]')"
if [ -n "$unamer" ]; then
    running_version="$(echo "$list" | awk "\$1 == \"$unamer\" { print \$2;exit; }")"
fi
# ignore the currently running version if attempting a reproducible build
if [ -n "${SOURCE_DATE_EPOCH}" ]; then
    unamer=""
    running_version=""
fi
latest_version="$(echo "$debverlist" | sed -n 1p)"
previous_version="$(echo "$debverlist" | sed -n 2,${NKER}p)"

debkernels="$(echo "$latest_version
$installed_version
$running_version
$previous_version" | sort -u | sed -e '/^$/ d')"
kernels="$( (echo "$1
$unamer"; for deb in $debkernels; do echo "$list" | awk "\$2 == \"$deb\" { print \$1; }"; done; ) \
   | sed -e 's#\([\.\+]\)#\\\1#g' -e '/^$/ d' | sort -u)"

generateconfig() {
    cat <<EOF
// DO NOT EDIT! File autogenerated by $0
APT::NeverAutoRemove
{
EOF
    for package in $(apt-config dump --no-empty --format '%v%n' 'APT::VersionedKernelPackages'); do
        for kernel in $kernels; do
            echo "   \"^${package}-${kernel}$\";"
        done
    done
    echo '};'
    if [ "${APT_AUTO_REMOVAL_KERNELS_DEBUG:-true}" = 'true' ]; then
        cat <<EOF
/* Debug information:
# dpkg list:
$(dpkg -l | grep '\(linux\|kfreebsd\|gnumach\)-image-')
# list of installed kernel packages:
$list
# list of different kernel versions:
$debverlist
# Installing kernel: $installed_version ($1)
# Running kernel: ${running_version:-ignored} (${unamer:-ignored})
# Last kernel: $latest_version
# Previous kernel: $previous_version
# Kernel versions list to keep:
$debkernels
# Kernel packages (version part) to protect:
$kernels
*/
EOF
    fi
}

generateconfig "$@" > "${config_file}.dpkg-new"
mv -f "${config_file}.dpkg-new" "$config_file"
chmod 444 "$config_file"

- Ravexina