LinuxShell学习简单小结(更新中……)

if-fi

#! /bin/bash # 删除文件和新建文件 file=readme function delFile(){ if [ -e ./$file ];then rm -f ./$file echo "del $file ..." fi } function addFile(){ if [ ! -f ./$file ];then touch $file echo "add $file ..." fi } delFile addFile

Result:

(没有readme文件)

[work shell]$ sh if_e.sh

add readme ...

[workshell]$ sh if_e.sh

del readme ...

add readme ...

===================================================

if-else-fi

#! /bin/bash echo "press y hello" read str if [ "$str" = "y" ] || [ "$str" = "Y" ];then echo "hello" else echo "bye.." fi;

Result:

[work shell]$ sh if.sh

press y hello

y

hello

[work shell]$ sh if.sh

press y hello

n

bye..

===================================================

if-elif-else-if（函数传参1）

# !/bin/sh

type=1    # 1, 2, 3(a,abc,123)


function getVal(){
    echo "$1"
}


if [ "$type" == "1" ]; then
    for((i=0;i<4;i++))
    do
        eval getVal $i
    done
elif [ "$type" == "2" ]; then
    echo "type"
else
    echo "none"
fi

Result:

yanggang@barry$

./param.sh

0

1

2

===================================================

if-elif-else-if（函数传参2）

# !/bin/sh

#type=1    # 1, 2, 3(a,abc,123)


function getVal(){
    echo "$1"
}

function inputVal(){
    if [ "$1" == "1" ]; then
        for((i=0;i<4;i++))
        do
            eval getVal $i
        done
    elif [ "$1" == "2" ]; then
        echo "type"
    else
        echo "none"
    fi
}

inputVal 1      # 1 is a param

Result:

yanggang@barry$

./param.sh

0

1

2

===================================================

case 条件

mysql

#!/bin/bash

case "$1" in
    start)
        echo "mysql start..."
        /etc/init.d/mysqld start
        ;;
    stop)
        echo "mysql stop..."
        /etc/init.d/mysqld stop
        ;;
    restart)
        echo "mysql restart..."
        /etc/init.d/mysqld stop
        /etc/init.d/mysqld start
        ;;
esac

exit 0

httpd

（apache）

#!/bin/bash

case "$1" in
    start)
        echo "apache start..."
        /etc/init.d/httpd start
        ;;
    stop)
        echo "apache stop..."
        /etc/init.d/httpd stop
        ;;
    restart)
        echo "apache restart..."
        /etc/init.d/httpd restart
        ;;
    status)
        echo "apache status"
        /etc/init.d/httpd status
        ;;
esac

exit 0

===================================================

awk

#! /bin/bash # 统计type类型文件，总共含有多少行 type="*.h *.cpp" result="result.txt" # 统计函数 function cal_lines() { rm -f $result #删除文件 for file in `ls $type`; do wc -l $file >> $result #新建并追加统计行数到文件 done awk '{total+=$1} END {print total}' $result >> $result #awk累加第一列，相加结果为total } cal_lines #调用函数 cat $result #查看结果

Result:

[work]$ sh cal_lines.sh

ls: *.h: No such file or directory

91 test_performance_server.cpp

178 test_performance_ubclient1.cpp

230 test_performance_ubclient2_common_async.cpp

204 test_performance_ubclient2_common_block.cpp

206 test_performance_ubclient2_common_nonblock.cpp

191 test_performance_ubclient2_common_single_block.cpp

193 test_performance_ubclient2_common_single_nonblock.cpp

237 test_performance_ubclient2_nshead_async.cpp

220 test_performance_ubclient2_nshead_block.cpp

218 test_performance_ubclient2_nshead_nonblock.cpp

192 test_performance_ubclient2_nshead_single_block.cpp

192 test_performance_ubclient2_nshead_single_nonblock.cpp

2352

===================================================

linux实现两个文件内容相加（3种解法）

a.txt（10行） b.txt（9行）

a.txt

b.txt

解法一

awk 'NR==FNR{a[NR]=$1; b[NR]=$2} NR > FNR{print $1 + a[FNR], $2+b[FNR]}' a.txt b.txt

运行结果：

[work]$

sh cal_ab1.sh

1 83

1 77

0 128

24 195

1 130

68 227

5 132

197 233

9 146

--------------------------------------------------------------------------------------

解法二

paste a.txt b.txt > c.txt while read a b c d; do echo $((a+c)) $((b+d)) done < c.txt

运行结果：

[work]$

sh cal_ab2.sh

1 83

1 77

0 128

24 195

1 130

68 227

5 132

197 233

9 146

0 8

--------------------------------------------------------------------------------------

解法三

paste a.txt b.txt | awk '{print $1+$3 "/t" $2+$4}'

运行结果：

[work]$

sh cal_ab3.sh

1       83

1       77

0       128

24      195

1       130

68      227

5       132

197     233

9       146

0       8

--------------------------------------------------------------------------------------

评析：

解法一，结果不准确，只输出了前9行

解法二，结果正确，但不够简洁

解法三，结果正确，简洁

===================================================

while循环

# !/bin/sh

TOP_NUM=800
index=0


function url_down(){

while [ $index -le $TOP_NUM ]
    do
       echo $index
        index=`expr $index + 24`
done

}

url_down

运行结果：

yanggang@barry$

./tmp.sh

0

24

48

72

96

120

144

168

192

216

240

264

288

312

336

360

384

408

432

456

480

504

528

552

576

600

624

648

672

696

720

744

768

792