jottings

#!/bin/env sh

[ -r /etc/hostname ] && source /etc/hostname
HOSTNAME=${hostname:-www.abc.com}
hostname $HOSTNAME

/etc/hostname
hostname=www.ibm.com

 ./filename.sh是生成子shell执行,设置当前bash的环境变量,必须使用 . 或source执行,才能生效

for p in /etc/profile.d/*.sh;do
           if [ -r "$p" ];then
                    . $p
            fi
done

: 类似于python中的pass,do nothing,return 0,即exit 0

if [ "$p" -eq 1 ];then
        :
else
        echo "$p not equal 1"
fi

echo $((2**4))

 

#!/bin/env sh

disks=$(fdisk -l /dev/[sh]d[a-z] | grep -o '^Disk /dev/[sh]d[a-z]' | wc --lines)

if [[ $disks -eq 1 ]];then
    fdisk -l /dev/[sh]da
else
    fdisk -l $(fdisk -l /dev/[sh]d[a-z] |grep -o '^Disk /dev/[sh]d[a-z]'|tail -1|cut -d' ' -f2)
fi