Shell脚本常用片段

CUR_DIR="$(dirname $0)"

if condition; then
    commands;
elif condition; then
    commands;
fi

date +%Y%m%d%H%M%S

# 纪元秒，方便用来实现简单的计时
date +%s

start=$(date +%s)
sleep 2
end=$(date +%s)

echo $[ end - start ]

function getTiming(){
    start=$1
    end=$2

    start_s=`echo $start| cut -d '.' -f 1`
    start_ns=`echo $start| cut -d '.' -f 2`
    end_s=`echo $end| cut -d '.' -f 1`
    end_ns=`echo $end| cut -d '.' -f 2`

    time_micro=$(( (10#$end_s-10#$start_s)*1000000 + (10#$end_ns/1000 - 10#$start_ns/1000) ))
    time_ms=`expr $time_micro/1000  | bc `

    echo "$time_micro microseconds"
    echo "$time_ms ms"
}

begin_time=`date +%s.%N`
sleep 1
end_time=`date +%s.%N`

getTiming $begin_time $end_time

if [ -f $file ]; then
    echo "$file exists"
else
    echo "$file does not exists"
f

if [ -d $dir ]; then
    echo "$dir exists"
else
    echo "$dir does not exists"
fi

appIds=(1 2 3 4 5 100)
for appId in ${appIds[@]}
do
    echo "${appId}"
done

length=${#fileArray[@]}

if [ ! -n "$1" ]; then
    echo "need one parameter"
else
    echo "parameter is $1"
fi

let newNum=$num+100

rm -rf all-808{1..9}.log
#生成连续IP地址
'%s,' 192.168.58.{1..255}