Avoid Multiple linux scripts

Avoid running linux scripts for multiple times-general Linux technology-Linux programming and kernel information. The following is a detailed description. #> Vi runonce

#/Bin/bash
# Determine whether a shell with the same name is being executed
PG = 'basename $0'
PN = 'ps-ef | grep "$ PG" | grep-v "grep" | awk' BEGIN {a = 0 ;}{ a ++ ;} END {print ()}''

# Normal execution if no duplicate instances exist
If [$ PN-le 0]
Then
Echo startup now!
If [-x $1]; then
. $1
Else
Echo excute access deny: $1
Fi
# If an instance is running, exit the instance.
Else
Echo already startup!
Exit 1;
Fi
Call runonce a. sh