linux - 将全局变量存储在 shell 脚本之外

Question

我的 shell 脚本有以下问题:每次我再次执行脚本时，变量 CURRENT 都会再次设置为 0，但是我怎样才能在每次脚本执行后保存 CURRENT？

#!/bin/sh
CURRENT=0
A='Knight rider'
B='Full color mood blobs'
C='Police Lights Single'
D='Police Lights Solid'
E='Rainbow mood'
F='Rainbow swirl'
G='Rainbow swirl fast'
H='Snake'
I='Strobe blue'

case $CURRENT in
    0) hyperion-remote --effect "$A"; CURRENT=$(( $CURRENT + 1 ));;
    1) hyperion-remote --effect "$B"; CURRENT=$(( $CURRENT + 1 ));;
    2) hyperion-remote --effect "$C"; CURRENT=$(( $CURRENT + 1 ));;
    3) hyperion-remote --effect "$D"; CURRENT=$(( $CURRENT + 1 ));;
    4) hyperion-remote --effect "$E"; CURRENT=$(( $CURRENT + 1 ));;
    5) hyperion-remote --effect "$F"; CURRENT=$(( $CURRENT + 1 ));;
    6) hyperion-remote --effect "$G"; CURRENT=$(( $CURRENT + 1 ));;
    7) hyperion-remote --effect "$H"; CURRENT=$(( $CURRENT + 1 ));;
    8) hyperion-remote --effect "$I"; CURRENT=0;;
esac

Answer 1

使用环境变量。

if [ -z "$CURRENT" ]; then
    CURRENT=0;
    export CURRENT;
else
    CURRENT=$CURRENT;
fi

不要忘记在脚本末尾更新 $CURRENT。