使用cmp命令比较include/generated/timestamp_autogenerated.h include/generated/timestamp_autogenerated.h.tmp两个文件(Linux中的cmp命令用于比较两个文件的不同，若发现两个文件有不同支出，则会标出来第一处不同的位置和列数编号；s或--quiet或--silent: 不显示错误信息)

全部展开，具体编译命令如下：

set -e; : '  CHK     include/generated/timestamp_autogenerated.h'; mkdir -p include/generated/;         (if test -n "${SOURCE_DATE_EPOCH}"; then SOURCE_DATE="@${SOURCE_DATE_EPOCH}"; DATE=""; for date in gdate date.gnu date; do ${date} -u -d "${SOURCE_DATE}" >/dev/null 2>&1 && DATE="${date}"; done; if test -n "${DATE}"; then LC_ALL=C ${DATE} -u -d "${SOURCE_DATE}" +'#define U_BOOT_DATE "%b %d %C%y"'; LC_ALL=C ${DATE} -u -d "${SOURCE_DATE}" +'#define U_BOOT_TIME "%T"'; LC_ALL=C ${DATE} -u -d "${SOURCE_DATE}" +'#efine U_BOOT_TZ "%z"'; LC_ALL=C ${DATE} -u -d "${SOURCE_DATE}" +'#define U_BOOT_DMI_DATE "%m/%d/%Y"'; LC_ALL=C ${DATE} -u -d "${SOURCE_DATE}" +'#define U_BOOT_BUILD_DATE 0x%Y%m%d'; else return 42; fi; else LC_ALL=C date +'#define U_BOOT_DATE "%b %d %C%y"'; LC_ALL=C date +'#define U_BOOT_TIME "%T"'; LC_ALL=C date +'#define U_BOOT_TZ "%z"'; LC_ALL=C date +'#define U_BOOT_DMI_DATE "%m/%d/%Y"'; LC_ALL=C date +'#define U_BOOT_BUILD_DATE 0x%Y%m%d'; fi) < Makefile > include/generated/timestamp_autogenerated.h.tmp; if [ -r include/generated/timestamp_autogenerated.h ] && cmp -s include/generated/timestamp_autogenerated.h include/generated/timestamp_autogenerated.h.tmp; then rm -f include/generated/timestamp_autogenerated.h.tmp; else : '  UPD     include/generated/timestamp_autogenerated.h'; mv -f include/generated/timestamp_autogenerated.h.tmp include/generated/timestamp_autogenerated.h; fi

include/generated/timestamp_autogenerated.h内容如下：