linux – EL 5上/etc/init.d/functions中声明的含义

当谈到Bash shell脚本时,我对业余爱好者感到困惑,并且对CentOS 5.10系统上/etc/init.d/functions中killproc()函数的第一行感到困惑：

local RC killlevel= base pid pid_file= delay try

那条线是什么意思？我相信它可能是局部变量的声明,但是在几个项目之后=的含义是什么？我在下面包含了完整的killproc()函数以供参考：

# A function to stop a program.
killproc() {
    local RC killlevel= base pid pid_file= delay try

    RC=0; delay=3; try=0
    # Test Syntax.
    if [ "$#" -eq 0 ]; then
        echo $"Usage: killproc [-p pidfile] [ -d delay] {program} [-signal]"
        return 1
    fi
    if [ "$1" = "-p" ]; then
        pid_file=$2
        shift 2
    fi
    if [ "$1" = "-d" ]; then
        delay=$(echo $2 | awk -v RS=' ' -v IGnorECASE=1 '{if($1!~/^[0-9.]+[smhd]?$/) exit 1;d=$1~/s$|^[0-9.]*$/?1:$1~/m$/?60:$1~/h$/?60*60:$1~/d$/?24*60*60:-1;if(d==-1) exit 1;delay+=d*$1} END {printf("%d",delay+0.5)}')
        if [ "$?" -eq 1 ]; then
            echo $"Usage: killproc [-p pidfile] [ -d delay] {program} [-signal]"
            return 1
        fi
        shift 2
    fi


    # check for second arg to be kill level
    [ -n "${2:-}" ] && killlevel=$2

        # Save basename.
        base=${1##*/}

        # Find pid.
    __pids_var_run "$1" "$pid_file"
    if [ -z "$pid_file" -a -z "$pid" ]; then
        pid="$(__pids_pidof "$1")"
    fi

        # Kill it.
        if [ -n "$pid" ] ; then
                [ "$BOOTUP" = "verbose" -a -z "${LSB:-}" ] && echo -n "$base "
        if [ -z "$killlevel" ] ; then
               if checkpid $pid 2>&1; then
               # TERM first, then KILL if not dead
               kill -TERM $pid >/dev/null 2>&1
               usleep 100000
               if checkpid $pid ; then
                try=0
                while [ $try -lt $delay ] ; do
                    checkpid $pid || break
                    sleep 1
                    let try+=1
                done
                if checkpid $pid ; then
                    kill -KILL $pid >/dev/null 2>&1
                    usleep 100000
                fi
               fi
                fi
            checkpid $pid
            RC=$?
            [ "$RC" -eq 0 ] && failure $"$base shutdown" || success $"$base shutdown"
            RC=$((! $RC))
        # use specified level only
        else
                if checkpid $pid; then
                        kill $killlevel $pid >/dev/null 2>&1
                RC=$?
                [ "$RC" -eq 0 ] && success $"$base $killlevel" || failure $"$base $killlevel"
            elif [ -n "${LSB:-}" ]; then
                RC=7 # Program is not running
            fi
        fi
    else
        if [ -n "${LSB:-}" -a -n "$killlevel" ]; then
            RC=7 # Program is not running
        else
            failure $"$base shutdown"
            RC=0
        fi
    fi

        # Remove pid file if any.
    if [ -z "$killlevel" ]; then
            rm -f "${pid_file:-/var/run/$base.pid}"
    fi
    return $RC
}

解决方法:

它只是声明了很多函数作用域变量,其中killlevel和pid_file被赋值为空字符串而其他函数没有被赋值.

有一点点差异.在从函数调用的函数中也可以看到局部变量.因此,如果您碰巧以递归方式调用killproc(),则会从调用者中记住未初始化的那些.

在Debian上,lib / lsb / init-functions文件如下所示：

killproc() {
    local pidfile sig status base name_param is_term_sig OPTIND
    pidfile=                                                   
    name_param=                                                
    is_term_sig=