copy file using tar

本文介绍了一种使用tar命令从源目录(source/dir)复制文件及子文件系统到目标目录(destination/dir)的方法。通过在源目录下运行tar命令进行打包,并在目标目录下解包的方式实现文件系统的完整迁移。
We assume /source/dir is a filesystem, if there are other filesystems under /source/dir they
will also be copied to /destination/dir

cd /source/dir
tar -cf - . | ( cd /destination/dir ; tar -xpvf - )
#!/bin/sh . /lib/functions.sh . /lib/config/uci.sh # initialize defaults RAMFS_COPY_BIN="" # extra programs for temporary ramfs root RAMFS_COPY_DATA="" # extra data files export INTERACTIVE=0 export VERBOSE=1 export SAVE_CONFIG=1 export SAVE_OVERLAY=0 export DELAY= export CONF_IMAGE= export CONF_BACKUP= export CONF_RESTORE= export NEED_IMAGE= export HELP=0 export FORCE=0 # parse options while [ -n "$1" ]; do case "$1" in -i) export INTERACTIVE=1;; -d) export DELAY="$2"; shift;; -v) export VERBOSE="$(($VERBOSE + 1))";; -q) export VERBOSE="$(($VERBOSE - 1))";; -n) export SAVE_CONFIG=0;; -c) export SAVE_OVERLAY=1;; -b|--create-backup) export CONF_BACKUP="$2" NEED_IMAGE=1; shift;; -r|--restore-backup) export CONF_RESTORE="$2" NEED_IMAGE=1; shift;; -f) export CONF_IMAGE="$2"; shift;; -F|--force) export FORCE=1;; -h|--help) export HELP=1; break;; -*) echo "Invalid option: $1" exit 1 ;; *) break;; esac shift; done export CONFFILES=/tmp/sysupgrade.conffiles export CONF_TAR=/tmp/sysupgrade.tgz export ARGV="$*" export ARGC="$#" [ -z "$ARGV" -a -z "$NEED_IMAGE" -o $HELP -gt 0 ] && { cat <<EOF Usage: $0 [<upgrade-option>...] <image file or URL> $0 [-q] [-i] <backup-command> <file> upgrade-option: -d <delay> add a delay before rebooting -f <config> restore configuration from .tar.gz (file or url) -i interactive mode -c attempt to preserve all changed files in /etc/ -n do not save configuration over reflash -F | --force Flash image even if image checks fail, this is dangerous! -q less verbose -v more verbose -h | --help display this help backup-command: -b | --create-backup <file> create .tar.gz of files specified in sysupgrade.conf then exit. Does not flash an image. If file is '-', i.e. stdout, verbosity is set to 0 (i.e. quiet). -r | --restore-backup <file> restore a .tar.gz created with sysupgrade -b then exit. Does not flash an image. If file is '-', the archive is read from stdin. EOF exit 1 } [ -n "$ARGV" -a -n "$NEED_IMAGE" ] && { cat <<-EOF -b|--create-backup and -r|--restore-backup do not perform a firmware upgrade. Do not specify both -b|-r and a firmware image. EOF exit 1 } # prevent messages from clobbering the tarball when using stdout [ "$CONF_BACKUP" = "-" ] && export VERBOSE=0 add_uci_conffiles() { local file="$1" ( find $(sed -ne '/^[[:space:]]*$/d; /^#/d; p' \ /etc/sysupgrade.conf /lib/upgrade/keep.d/* 2>/dev/null) \ -type f 2>/dev/null; opkg list-changed-conffiles ) | sort -u > "$file" return 0 } add_overlayfiles() { local file="$1" find /overlay/etc/ -type f | sed \ -e 's,^/overlay/,/,' \ -e '\,/META_[a-zA-Z0-9]*$,d' \ -e '\,/functions.sh$,d' \ -e '\,/[^/]*-opkg$,d' \ > "$file" return 0 } # hooks sysupgrade_ipf_pre_upgrade="platform_pre_upgrade" sysupgrade_sdk_pre_upgrade="sdk_pre_upgrade" sysupgrade_image_check="platform_check_image" [ $SAVE_OVERLAY = 0 -o ! -d /overlay/etc ] && \ sysupgrade_init_conffiles="add_uci_conffiles" || \ sysupgrade_init_conffiles="add_overlayfiles" include /lib/upgrade do_save_conffiles() { local conf_tar="${1:-$CONF_TAR}" [ -z "$(rootfs_type)" ] && { echo "Cannot save config while running from ramdisk." ask_bool 0 "Abort" && exit return 0 } run_hooks "$CONFFILES" $sysupgrade_init_conffiles ask_bool 0 "Edit config file list" && vi "$CONFFILES" v "Saving config files..." [ "$VERBOSE" -gt 1 ] && TAR_V="v" || TAR_V="" tar c${TAR_V}zf "$conf_tar" -T "$CONFFILES" 2>/dev/null } if [ -n "$CONF_BACKUP" ]; then do_save_conffiles "$CONF_BACKUP" exit $? fi if [ -f "$CONF_RESTORE" ] || [ "$CONF_RESTORE" = "-" ]; then [ "$VERBOSE" -gt 1 ] && TAR_V="v" || TAR_V="" tar -C / -x${TAR_V}zf "$CONF_RESTORE" exit $? fi type platform_check_image >/dev/null 2>/dev/null || { echo "Firmware upgrade is not implemented for this platform." exit 1 } for check in $sysupgrade_image_check; do ( eval "$check \"\$ARGV\"" ) || { if [ $FORCE -eq 1 ]; then echo "Image check '$check' failed but --force given - will update anyway!" break else echo "Image check '$check' failed." exit 1 fi } done if [ -n "$CONF_IMAGE" ]; then case "$(get_magic_word $CONF_IMAGE cat)" in # .gz files 1f8b) ;; *) echo "Invalid config file. Please use only .tar.gz files" exit 1 ;; esac get_image "$CONF_IMAGE" "cat" > "$CONF_TAR" export SAVE_CONFIG=1 elif ask_bool $SAVE_CONFIG "Keep config files over reflash"; then do_save_conffiles export SAVE_CONFIG=1 else export SAVE_CONFIG=0 fi run_hooks "" $sysupgrade_ipf_pre_upgrade run_hooks "" $sysupgrade_sdk_pre_upgrade local upgrade_type=$(uci get profile.@global[0].upgrade_type -c /etc/profile.d) RAMFS_COPY_BIN="$RAMFS_COPY_BIN $RAMFS_COPY_BIN_PRD $RAMFS_COPY_BIN_PLAT" RAMFS_COPY_DATA="$RAMFS_COPY_DATA $RAMFS_COPY_DATA_PRD $RAMFS_COPY_DATA_PLAT" RAMFS_COPY_DIR="$RAMFS_COPY_DIR_PRD $RAMFS_COPY_DIR_PLAT" if [ -n "$(rootfs_type)" -a "$upgrade_type" == "ramfs_up" ]; then kill_remaining TERM sleep 3 kill_remaining KILL v "Switching to ramdisk..." run_ramfs '. /lib/functions.sh; include /lib/upgrade; do_upgrade' else do_upgrade fi 上述代码是openwrt中rootfs的sysupgrade代码,请逐行给出详细解释说明,以注释的形式给出
09-23
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