linux shell script 例子1

1. 如何获得脚本参数：
#!/bin/she
#
while [ -n "$1" ]
do
case "$1" in
-a) echo "found the -a option";;
-b) param="$2"
echo "found the -b option";;
-c) echo "found the -c option";;
--) shift
break;;
*) echo "$1 is not an option";;
esac
shift
done
count=1
for para in "#@"
do
echo "parameter #$count : $para"
count=$[ $count + 1 ]
done
2.判断输入是否符合条件：
 #!/bin/sh
#
read input
if [[ $input == r* && ${#input} -eq 10 ]]; then #check the input character bits
echo "yes, your input right."
else
echo "no ,your input error."
fi
3.如何让用户输入，如果你想得到用户输入一定要记得read command.
 #!/bin/sh
#
#
read -n1 -t 10 -p "Do you want to continue [Y/N]?" answer
case $answer in
Y | y) echo
echo "fine, continue on ... ";;
N | n) echo
echo "ok, goodbye
exit;;
esac
echo "this is the end of the script"
 4.从文件中读出数据
#!/bin/sh
#
#
#
count=1
cat testfile | while read line
do
echo "Line $count : $line"
count=$[ $count + 1 ]
done
echo "finished processing the file"
#you can also use the read command to read data stored in a file on the linux system. each call to the read command reads a single line of text from the file. when there are no more lines left in the file,the read command will exit with a non-zero exit status.
5.创建自己的重定向文件描述符
#!/bin/bash
# storing STDOUT, then coming back to it
exec 3>&1
exec 1>test14out
echo "This should store in the output file"
echo "along with this line."
exec 1>&3
echo "Now things should be back to normal"
#This example is a little crazy, so let’s walk through it piece by piece. First, the script redirects file descriptor 3 to the current location of file descriptor 1, which is STDOUT. This means that any output sent to file descriptor 3 will go to the monitor.The second exec command redirects STDOUT to a file. The shell will now redirect any output se