shell程序设计.doc

实验二 shell程序设计【实验目的】（1） 掌握shell的概念，了解shell的工作原理（2） 熟悉shell环境（3） 掌握基本的shell程序设计【基础知识】1、if语句（1）判断输入的是目录、文件还是其它，如果是文件，获取文件的读写执行权限#! /bin/bash#an example script of ifclearecho input a file or directory name,plsread path_nameif -d $path_name then echo $path_name is a directoryelif -f $path_name then echo $path_name is a regular file if -r $path_name then echo $path_name is a readable file fi if -w $path_name then echo $path_name is a writeable file fi if -x $path_name then echo $path_name is a executeable file fielse echo this script cannot get the file/directory( $path_name) information!fi2. 以shell返回值作为判断条件，判断能否进入输入的目录#! /bin/bash#another example script of ifecho input a directory, plsread dir_nameif cd $dir_name /dev/null 2&1then echo enter directory: $dir_name succeedelse echo enter directory: $dir_name failedfi3. case语句，判断输入值的几种状态#! /bin/bash#an example script of caseclearecho Do you like Linux?read like_itcase $like_it iny|Y|yes|Yes) echo Linux is a good friend of us. ;n|N|no|No) echo Try it, and you will like it. ;* ) echo your answer is: $like_it ;esac 4. for循环（1）列表值在程序中#! /bin/bash#an example script of FORclearfor os in Linux Windows UNIX MACdo echo Operation System is: $osdone（2）列表值通过命令行参数列表传入#! /bin/bash#an example script of FOR without arglistclearfor os do echo Operation System is: $osdone5. while和until循环（1）while循环#! /bin/bash#an example script of whileclearloop=0while $loop -ne 10 do let loop=$loop+1 echo current value of loop is: $loop done（2）until循环#! /bin/bash#an example script of untilclearloop=0until $loop -eq 10 do let loop=$loop+1 echo current value of loop is: $loop done6. 函数调用及参数传递（1）利用数组使用参数#! /bin/bash#an example script of functionfunction demo_fun() echo Your command is: $0 $* echo Number of parameters($#) is: $# echo Parameters($*) is: $* echo Parameters($) is: $ count=1 for param in $ do echo Parameters($count) is: $param let count=$count+1 donecleardemo_fun $(2) 利用shift操作使用参数#! /bin/bash#an example script of functionfunction demo_fun() echo Your command is: $0 $* echo Number of parameters($#) is: $# echo Parameters($*) is: $* echo Parameters($) is: $ count=1 while -n $1 do echo Parameters($count) is: $1 let count=$count+1 shift donecleardemo_fun $7. 函数返回值（1）显示返回#! /bin/bash#an example script of returnfunction fun_return() dir_name=$1 rtn_value=0 if ! cd $dir_name /dev/null 2&1; then rtn_value=1 fi return $rtn_valueclearif fun_return $; then echo function executes sucessfully!else echo function executes failed!fi（2）隐式返回#! /bin/bash#an example script of returnfunction fun_return() dir_name=$1 cd $dir_name /dev/null 2&1 returnclearif fun_return $; then echo function executes sucessfully!else echo function executes failed!fi8. 综合练习：文件备份脚本#! /bin/bash#an example script of backup filesLOG_START_TIME=date +%Y%m%d%H%M%SBACKUP_DIR=/Lesson10/backupBACKUP_LOG=$BACKUP_DIR/$LOG_START_TIME.logfunction write_log() log_time=date +%Y-%m-%d-%H-%M-%s backup_file_name=$2 err_msg=$log_time ERROR in backup file/directory($backup_file_name) suc_msg=$log_time SUCCESS in backup file/directory($backup_file_name) if $1 -eq 0 ;then echo $suc_msg echo $suc_msg $BACKUP_LOG else echo $err_msg echo $err_msg $BACKUP_LOG fifunction backup_file() cp -fr $1 $BACKUP_DIR /dev/null 2&1 write_log $? $1function create_log_file() if ! -e $BACKUP_DIR ;then mkdir $BACKUP_DIR fi if -e $BACKUP_LOG ; then rm -f $BACKUP_LOG fi touch $BACKUP_LOGclearecho Backup Process Beginscreate_log_filefor file in $do backup_file $filedoneecho Backup Process ends【实验内容】1.带一个(目录)参数，可浏览目录下的内容。(lsdir.sh)实现功能：(1)首先判断(if)是否带有参数，若无则显示(echo)用法信息后，报错返回(exit)；(2)首先判断该参数是不是目录。若是则列目录的内容(ls)，否则，提示用户不是目录，则显示警告信息后报错返回。运行：设程序名为lsdir.sh，为其增加执行权chmod 755 lsdir.sh运行：./lsdir.sh./lsdir.sh dir#如果dir是个目录，则列其内容./lsdir.sh file#若file是文件或不存在则给出警告后返回2. 只用嵌套结构if-fi实现上述程序 (lsdirif.sh)3、带数值参数，并可计算这些数值参数的和 (sum.sh)4、计算前n个正整数的和 (sum_n.sh)注：此程序带有1个参数作为整数n，以计算1至n个正整数的和5、编写Shell程序 (setmod.sh)，在/home目录下建立10个目录，即u