生成备份文件时所使用的脚本中调用的命令为sysgrade

   local image_tmp   = "/tmp/firmware.img"

   local backup_cmd  = "sysupgrade --create-backup - 2>/dev/null"

   local fsysup = "openwrt-ar71xx-generic-ap143-16M-squashfs-sysupgrade.bin"

   local fwname = "firmware.tar.gz"

   local image_tmp_gz   = "/tmp/"..fwname

最后将文件压缩为 backup-hostname-date.tar.gz    (eg:  backup-openwrt-2016-01-09.tar.gz)

    luci.sys.exec("cd /tmp; tar -zxvf "..fwname.."; mv "..fsysup.." "..image_tmp.."; rm "..image_tmp_gz)

其中压缩文件.tar.gz中包含的内容有：  lib/upgrade/keep.d/ 目录下文件中所有的内容以及  etc/sysupgrade.conf中包含的内容

主要有：

# cd lib/upgrade/keep.d/

# ls

base-files            uboot-envtools

base-files-essential  uhttpd

# cat base-files

/etc/config/            --config目录下所有文件

/etc/dropbear/       --dropbear目录下所有文件

/etc/crontabs/        --crontabs目录下所有文件

# cat base-files-essential   

# Essential files that will be always kept

/etc/hosts              --etc目录下的这些文件

/etc/inittab

/etc/group

/etc/passwd

/etc/profile

/etc/shadow

/etc/shells

/etc/sysctl.conf

/etc/rc.local

# cat uboot-envtools

/etc/config/ubootenv    --uboot相关文件

/etc/fw_env.config

# cat uhttpd

/etc/uhttpd.crt                  --uhttpd相关文件

/etc/uhttpd.key

如果还想备份其他文件，可以在/etc目录下的sysupgrade.conf中添加相应目录或文件。

将备份的压缩文件解压后可以看到

tar zxvf backup-openwrt-2016-01-19.tar.gz

etc/config/account

etc/config/checkrssi

etc/config/dropbear

etc/config/firewall

etc/config/link.log

etc/config/lldpd

etc/config/luci

etc/config/mcs

etc/config/network

etc/config/snmpd

etc/config/snmpdata

etc/config/system

etc/config/ubootenv

etc/config/ucitrack

etc/config/uhttpd

etc/config/wireless

etc/config/wonoff

etc/crontabs/cron.update

etc/crontabs/root

etc/dropbear/dropbear_dss_host_key

etc/dropbear/dropbear_rsa_host_key

etc/fw_env.config

etc/group

etc/hosts

etc/inittab

etc/passwd

etc/profile

etc/rc.local

etc/shadow

etc/shells

etc/sysctl.conf

etc/sysupgrade.conf

etc/uhttpd.crt

etc/uhttpd.key

 

如果在sysupgrade.conf中添加 /overlay目录则：

# cat sysupgrade.conf

## This file contains files and directories that should

## be preserved during an upgrade.

# /etc/example.conf

# /etc/openvpn/

/overlay     --将overlay目录下的文件压缩到备份中

 

解压备份文件可得

tar zxvf backup-openwrt-2016-01-19.tar.gz

etc/config/account

etc/config/checkrssi

etc/config/dropbear

etc/config/firewall

etc/config/link.log

etc/config/lldpd

etc/config/luci

etc/config/mcs

etc/config/network

etc/config/snmpd

etc/config/snmpdata

etc/config/system

etc/config/ubootenv

etc/config/ucitrack

etc/config/uhttpd

etc/config/wireless

etc/config/wonoff

etc/crontabs/cron.update

etc/crontabs/root

etc/dropbear/dropbear_dss_host_key

etc/dropbear/dropbear_rsa_host_key

etc/fw_env.config

etc/group

etc/hosts

etc/inittab

etc/passwd

etc/profile

etc/rc.local

etc/shadow

etc/shells

etc/sysctl.conf

etc/sysupgrade.conf

etc/uhttpd.crt

etc/uhttpd.key

overlay/etc/config/account

overlay/etc/config/checkrssi

overlay/etc/config/dropbear

overlay/etc/config/firewall

overlay/etc/config/link.log

overlay/etc/config/lldpd

overlay/etc/config/luci

overlay/etc/config/mcs

overlay/etc/config/network

overlay/etc/config/snmpd

overlay/etc/config/snmpdata

overlay/etc/config/system

overlay/etc/config/ubootenv

overlay/etc/config/ucitrack

overlay/etc/config/uhttpd

overlay/etc/config/wireless

overlay/etc/config/wonoff

overlay/etc/crontabs/cron.update

overlay/etc/crontabs/root

overlay/etc/dropbear/dropbear_dss_host_key

overlay/etc/dropbear/dropbear_rsa_host_key

overlay/etc/fw_env.config

overlay/etc/group

overlay/etc/hosts

overlay/etc/inittab

overlay/etc/passwd

overlay/etc/profile

overlay/etc/rc.local

overlay/etc/shadow

overlay/etc/shells

overlay/etc/sysctl.conf

overlay/etc/sysupgrade.conf

overlay/etc/uhttpd.crt

overlay/etc/uhttpd.key

overlay/root/logs

overlay/usr/lib/snmp/snmpd.conf

etc/uhttpd.key

etc/uhttpd.crt