在脚本中判断电脑是否插了电源
（针对Debian/Ubuntu发行版）
以下的代码可以判断电脑是否电池供电（来自于/etc/cron.daily/mlocate，apt 也使用了类似的脚本）：
|
1 2 3 4 5 6 7 |
if which on_ac_power >/dev/null 2>&1; then ON_BATTERY=0 on_ac_power >/dev/null 2>&1 || ON_BATTERY=$? if [ "$ON_BATTERY" -eq 1 ]; then exit 0 fi fi |
这段脚本使用“on_ac_power”这个小工具来判断是否AC电源供电。这个工具属于包“powermgmt-base”，默认安装。“on_ac_power”没有参数，启动后没有屏幕输出，通过返回值来发挥结果：
- 0（zero）：电源供电
- 1（one）：电源供电
- 255：程序无法判断
这个工具位于“/sbin/”目录下，同时在“/usr/bin/”目录下有一个符号链接指向前者。也是一个 Bash 脚本，不到一百行代码，通过“/proc/”目录中的信息来进行判断。
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 |
#!/bin/sh # # Returns 0 (true) if on AC power # 1 (false) if not on AC power # 255 (false) if can't tell # # Example shell script: # if on_ac_power; then # echo We're on AC power # else # echo Can't say we're on AC power # fi set -e # sysfs # # This algorithm is complicated by the possibility of multiple AC # adapters. We scan the ac_adapter/power_supply directory looking for adapters # that have known states. If any adapter is on-line, we return 0. If # no adapters are on-line but one or more are off-line, we return 1. # OFF_LINE_P=no if [ -d /sys/class/power_supply/ ]; then for FN in /sys/class/power_supply/*; do if test -d "${FN}" && test -r "${FN}/type"; then type="$(cat ${FN}/type)" if test "x${type}" = "xMains"; then if [ -r "${FN}/online" ]; then online="$(cat ${FN}/online)" [ "$online" = 1 ] && exit 0 [ "$online" = 0 ] && OFF_LINE_P=yes fi fi fi done [ "${OFF_LINE_P}" = "yes" ] && exit 1 fi # ACPI # same algorithm as above, a fallback only when the generic sysfs interface # is not available (old kernels only) if /sbin/acpi_available && [ -d /proc/acpi/ac_adapter ]; then for FN in /proc/acpi/ac_adapter/*; do if [ -d "${FN}" ]; then if [ -r "${FN}/state" ]; then grep --quiet on-line "${FN}/state" && exit 0 grep --quiet off-line "${FN}/state" && OFF_LINE_P=yes elif [ -r "${FN}/status" ]; then grep --quiet on-line "${FN}/status" && exit 0 grep --quiet off-line "${FN}/status" && OFF_LINE_P=yes fi fi done [ "${OFF_LINE_P}" = "yes" ] && exit 1 fi # PMU if [ -r /proc/pmu/info ]; then exec awk </proc/pmu/info ' BEGIN { FS=":"; ret = 255 } /^AC Power.*1$/ { ret = 0; exit } /^AC Power.*0$/ { ac = 1 } /^Battery.*/ { if ($2 ~/0/ && ac == 1) ret = 0 else ret = 1 exit } END { exit ret } ' fi # APM if [ -r /proc/apm ] && /sbin/apm_available; then exec awk </proc/apm ' BEGIN { ret = 255 } /^[0-9.a-zA-Z]* [0-9.]* 0x.. 0x../ { if ($4 == "0x01") { ret = 0; exit } else if ($4 == "0x00") { ret = 1; exit } } END { exit ret } ' fi # nothing is available exit 255 |
Recent Comments