对于Bash shell脚本而言,我是业余爱好者,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
}
答案 0 :(得分:5)
它只是声明了很多函数作用域变量,其中killlevel
和pid_file
被赋予空字符串而其他函数没有被分配任何内容。
略有不同。在从函数调用的函数中也可以看到local
个变量。因此,如果您碰巧以递归方式调用killproc()
,则会从调用方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=