如何使Shell脚本只有一个实例在运行

LOCKFILE=/tmp/lock.txtif [ -e ${LOCKFILE} ] && kill -0 `cat ${LOCKFILE}`; then    echo "already running"    exitfi# make sure the lockfile is removed when we exit and then claim ittrap "rm -f ${LOCKFILE}; exit" INT TERM EXITecho $$ > ${LOCKFILE}################## your stuff here#################rm -f ${LOCKFILE}

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