Linux shell 示例（一）

一、环境
系统：Centos6.6 x64
shell：bash、sh

[centos@Shell ~]$ hostname
Shell
[centos@Shell ~]$ lsb_release -a
LSB Version:    :base-4.0-amd64:base-4.0-noarch:core-4.0-amd64:core-4.0-noarch:graphics-4.0-amd64:graphics-4.0-noarch:printing-4.0-amd64:printing-4.0-noarch
Distributor ID: CentOS
Description:    CentOS release 6.6 (Final)
Release:    6.6
Codename:   Final
[centos@Shell ~]$ echo $SHELL
/bin/bash
[centos@Shell ~]$ ifconfig eth0 |grep "t addr"| awk -F '[: ]+' '{print $4}'
192.168.101.110

二、脚本示例
1、终端打印

#!/bin/bash
#The printf of Linux termnal,Include "echo,printf"
#author by woon 
echo "The shell\`s name is $0"

#examples of echo,printf
#默认打印。输出换行
echo "Hello World!" 
echo 'Hello World!'
#echo -n参数接受不换行输出
echo -n "Hello World"
echo "Hello World"
#-e参数接受双引号内字符串的转移列表
echo "Hello\tWorld!"
echo -e "Hello\tWorld!"
#printf使用文本或由空格分割的参数，可指定输出的宽度、对其方式等，可以格式化输出，默认情况下，printf不输出换行
printf "%-5s %-10s %-4s\n" No. NAME Mark
printf "%-5s %-10s %-4s\n" 1 Lee 80
printf "%-5s %-10s %-4.2f\n" 2 Woon 90.456
printf "%-5s %-10s %-4.2f\n" 3 James 85.654321
printf "%-5s %-10s %-5.3f\n" 4 Jeff 85.123789

运行结果：

The shell`s name is shell_print.sh
Hello World!
Hello World!
Hello WorldHello World
Hello   World!
-e Hello    World!
No.   NAME       Mark
1     Lee        80  
2     Woon       90.46
3     James      85.65
4     Jeff       85.124

2、环境变量

#!/bin/bash
#author by woon
#env#获取全局环境变量
env > /tmp/env_$(date +%Y%m%d).$$
head -n 10 /tmp/env_$(date +%Y%m%d).$$
echo "^^^^^^^^^^^^^^^^^分隔符^^^^^^^^^^^^^^^^^^^^^^" 
#获取单个全局变量的值
echo $PATH
echo "^^^^^^^^^^^^^^^^^分隔符^^^^^^^^^^^^^^^^^^^^^^"
#自定义变量和自定义全局变量,删除环境变量
var="Hello World"
echo -n "$var" 
echo -n $var
echo ${var}
#设置全局环境变量
export VAR

#获取当前的shell版本
echo $SHELL
#or
echo $0
#获取变量的长度
var="Hello World"
echo ${#var}

#变量内容的删除
path=$PATH
echo $path
echo "最短删除，非贪婪模式,由前向后删除"
var1=${path#/*:}
echo $var1
echo "贪婪模式，删除匹配到最长的，由前向后删除"
var2=${path##/*:}
echo $var2
echo "非贪婪模式%，由后向前删除"
var3=${path%:*bin}
echo $var3

echo "贪婪模式，由后向前删除最长的"
var4=${path%%:*bin}
echo $var4

3、shell数学运算

#!/bin/bash
#author by woon.
#数学运算
sum_jia=0
sum_cheng=1
i=1

while [ $i -le 10 ]; 
do
     let "sum_jia+=i"
     let "sum_cheng*=i"
     let "i += 2"
done
sum_jian1=$[ sum_cheng - sum_jia]
sum_jian2=$(( sum_cheng - sum_jia ))

echo $sum_jia
echo $sum_cheng
echo $sum_jian1
echo $sum_jian2

运行结果
$ ./shell_num.sh
25
945
920
920

4、文件查找和文件列表几操作

#!/bin/bash
#author by woon
#find 可以基于名字、类型、时间、大小、目录深度、大小权限、用户等查找并执行动作
#example

sudo find /etc/ -iregex ".*\(\.py\|\.sh\)" -type f  -atime -1 -user root -size -2k -perm 644 -print
#sudo find /etc/ -iregex ".*\(\.py\|\.sh\)" -type f  -atime -1 -user root -size -2k -perm 644 -delete
sudo find /etc/ -iregex ".*\(\.py\|\.sh\)" -type f  -atime -1 -user root -size -2k -perm 644 -exec ll {} \;
sudo find /etc/ -iregex ".*\(\.py\|\.sh\)" -type f  -atime -1 -user root -size -2k -perm 644 -print0 | xargs -0  ls -l

5、tr转换
tr参数属于集合映射关系
tr删除

[centos@Shell scripts]$ uuidgen | tr -d [a-z]
37643-2050-48-25-547825

tr替换
本替换其实值将0-a、1-b …… 9-j的映射关系替换

[centos@Shell scripts]$ echo | md5sum |tr [0-9] [a-z]
gibdcjdajijdedeajjchdiadfcbjcjea  -

6、校验和核实
md5sum

[centos@Shell scripts]$ ls
dialog_t.md5  os_monitor-dialog.sh  shell_print.sh    test.sh
dialog_t.sh   pcpu_usage.sh         shell_search.sh   top10_commands.sh
inpath        shell_num.sh          shell_varable.sh
[centos@Shell scripts]$ md5sum os_monitor-dialog.sh >os_monitor-dialog.md5
[centos@Shell scripts]$ md5sum -c os_monitor-dialog.md5 
os_monitor-dialog.sh: 确定

脚本示例

#!/bin/bash
#为/etc/passwd生成一个MD5并校验，在生成MD5前检查/etc/passwd文件是否已经被排过序

sort -C /etc/passwd
if [ $? -eq 0 ]; then
        echo "Sorted"
else
        echo "Unsorted!"
        md5sum /etc/passwd > passwd.md5
fi
md5sum -c passwd.md5

7、生成随机数
$RANDOM生成一个随机数；date +%s%N获取随机数字字符串
脚本如下：

#!/bin/bash
#创建example目录，在该目录下批量生成10个日志文件，日志文件名包含10个随机小写字母和固定字符串example;当前用户不具有权限，需要设置权限
if [ ! -d /example ]; then
        echo "centos"|sudo -S mkdir /example
        echo "centos" | sudo -S chown centos:centos /example -R
fi
#产生随机数$RANDOM，或uuidgen命令或者用MD5sum，然后替换
for num in $(seq 1 10)
do
         touch /example/$(echo $RANDOM | md5sum |tr "0-9" "a-z"|cut -c 1-10)_example.log
done

8、根据扩展名切分文件名

#!/bin/bash
#shell name：shell_split.sh
#切分文件名并批量重命名或移动,比如图形文件等
num=1；
for img in *.jpg *.img
do
        mv $img image-$num.{img##*.} 2>/dev/null
        if [ $? -eq 0 ]; then
                echo  "Rename $img to image-$num.${img##*.}"
                let num++
        fi

done

9、列举文件类型统计信息
给出一个路径，统计该路径下各文件类型的数量

#!/bin/bash
#shell name:shell_filestat.sh
#列举文件类型数量

if [ $# -ne 1 ]; 
then
    echo -e "$0 path\nexample:$0 /etc/"
else
    path=$1
    declare -A array;
while read line;
do
#echo $(file -b $line)
    ftype=$(file -b $line)
    let array["$ftype"]++;
done< <(find $path -type f -print)
fi
echo ========== File types and counts ===========
for ftype in "${!array[@]}"
do
    echo $ftype : ${array["$ftype"]}
done

10、判断当前系统是否支持该命令

#!/bin/sh

in_path()
{

  cmd=$1        path=$2         retval=1
  oldIFS=$IFS   IFS=":"

  for directory in $path
  do
    if [ -x $directory/$cmd ] ; then
      retval=0  
    fi
  done
  IFS=$oldIFS
  return $retval
}

checkForCmdInPath()
{
  var=$1

  if [ "$var" != "" ] ; then
    if [ "${var%${var#?}}" = "/" ] ; then
      if [ ! -x $var ] ; then
        return 1
      fi
    elif ! in_path $var $PATH ; then
      return 2
    fi
  fi
}

if [ $# -ne 1 ] ; then
 echo "Usage: $0 command" >&2 ; exit 1
fi

checkForCmdInPath "$1"
case $? in
  0 ) echo "$1 found in PATH"                  ;;
  1 ) echo "$1 not found or not executable"    ;;
  2 ) echo "$1 not found in PATH"              ;;
esac

exit 0