SHELL中函数的写法、调用、参数、返回值代码范例

get_pid()
{
    process_name=$1
    text=`ps -A | grep $process_name`
    # 去掉开头的空格
    text=`echo $text | sed -e 's/^[ \t]*//g'`
    # 得到进程号之后的空格
    pos=`expr index "$text" " "`
    pos=`expr $pos - 1`
    #截取进程号
    pid=`echo $text | cut -c 1-$pos`
    #echo pid=---$pid+++
    echo $pid
    return 0
}
get_mem()
{
    process_id=$1
    text=`cat /proc/$process_id/status | grep VmRSS`
    pos=`expr index "$text" " "`
    text=`echo $text | cut -c $pos-`
    pos=`expr index "$text" " "`
    pos=`expr $pos - 1`
    memory=`echo $text | cut -c 1-$pos`
    #echo memory=---$memory+++
    echo $memory
    return 0
}
# 最好是参数传递
PROCESS_NAME="gh_main"
pid=$(get_pid $PROCESS_NAME)
old_memory=$(get_mem $pid)
echo pid=$pid, mem=$old_memory
# 循环。如果内存变化，输出变化情况。
while [ true ] ; do
    new_memory=$(get_mem $pid)
    if [ $new_memory -ne $old_memory ] ; then
        # 便于观察
        echo
        echo ---------------------------------
        date
        diff=`expr $new_memory - $old_memory`
        echo $old_memory - $new_memory = $diff
        old_memory=$new_memory
    fi
done