Loops for and while && User interfaces

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for

实例

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#!/bin/bash
for i in 1 2 3 4 5
do
   echo "Welcome $i times"
done

for i in $( ls ); do
    echo item: $i
done

for i in `seq 1 10`;
do
    echo $i
done

for i in {1..5}
do
   echo "Welcome $i times"
done

for (( c=1; c<=5; c++ ))
do
	echo "Welcome $c times..."
done
for i in {0..10..2}
do
    echo "Welcome $i times"
done

for i in $(seq 1 2 20)
do
   echo "Welcome $i times"
done

单行实例

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for ((i=1; $i<=9;i++)); do echo $i; done

for ip in {1..10};do echo $ip; done

for i in `seq 1 10`;do echo $i;done

for ip in {81..92}; do ssh root@172.16.3.$ip date; done

for n in  {23..32} {49,50} {81..92}; do mkdir /tmp/$n; echo $n; done

—>backup file

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#!/bin/bash
FILES="$@"
for f in $FILES
do
        # if .bak backup file exists, read next file
	if [ -f ${f}.bak ]
	then
		echo "Skiping $f file..."
		continue  # read next file and skip cp command
	fi
        # we are hear means no backup file exists, just use cp command to copy file
	/bin/cp $f $f.bak
done

while

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#!/bin/bash
COUNTER=0
while [  $COUNTER -lt 10 ]; do
    echo The counter is $COUNTER
    let COUNTER=COUNTER+1
done
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while read name age
do
	echo $name $age
done << EOF
neo 30
jam 31
john 29
EOF


while read name age
do
	[[ $age -gt 30 ]] && echo $name
done << EOF
neo 30
jam 31
john 29
EOF
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$ cat mount.sh
#!/bin/sh
while read LINE
do

	s=`echo $LINE|awk '{print $1}'`
	d=`echo $LINE|awk '{print $2}'`

	umount -f $d
	mount -t nfs4 $s $d

done < mount.conf

$ cat mount.conf
172.16.0.1:/	/www/logs/1
172.16.0.2:/	/www/logs/2
172.16.0.3:/	/www/logs/3
172.16.0.4:/	/www/logs/4
172.16.0.5:/	/www/logs/5

User interfaces

using select to make simple menus:

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#!/bin/bash
OPTIONS="Hello Quit"
select opt in $OPTIONS; do
    if [ "$opt" = "Quit" ]; then
     echo done
     exit
    elif [ "$opt" = "Hello" ]; then
     echo Hello World
    else
     clear
     echo bad option
    fi
done

read
input your name in 30s

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$ read -p "Please input your name: " -t 30 named
Please input your name: neo

$ echo $named