shell和定时任务

---

while read line; do echo `echo $line | awk -F ':' '{print $1}'` hello; done < /etc/passwd

while read line; do echo $line; echo "--------------"; done < /etc/passwd

for ((i=1;i<=9;i++)); do for ((y=1;y<=i;y++)); do echo -n -e "$y*$i=$((i*y))\t"; done; echo ""; done

for i in 1 2 3 10 ; do echo $i; done

a=1
b=2
c=3

echo "$a $b $c"
echo $a $b $c
echo "$a+$b+$c"
echo "$($a+$b+$c)"
echo "$((a+b))"
echo "$((c+b))"
echo "$(($c+$b))"
echo "$[[$c+$b]]"
echo "$[$c+$b]"
expr $a + $b
[ $a = $b ];echo $?
[ $a != $b ];echo $?
[ -z $a ];echo $?
[ -n $a ];echo $?
[ $a -eq $b ];echo $?
[ $a -nq $b ];echo $?
[ $a -ne $b ];echo $?
[ $a -lt $b ];echo $?
[ $a -gt $b ];echo $?
(($a>$b));echo $?
(($a<$b));echo $?
[ -f /etc/passwd ];echo $?
[ -e /etc/passwd ];echo $?
[ -e /etc/passwdd ];echo $?
date
date '+%Y%m%d-%H%M'

---