Linux Shell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 ...
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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..
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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"
fiResult:
yanggang@barry$ ./param.sh 0 1 2
3
===================================================
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 [ "$1" == "2" ]; then
echo "type"
else
echo "none"
fi
}
inputVal 1 # 1 is a paramResult:
yanggang@barry$ ./param.sh
0 1 2
3 ===================================================
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 0httpd（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
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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
-------------------------------------------------------------------------------
参考拓展：
Linux Make（Makefile）由浅入深的学习与示例剖析
参考推荐： Linux Shell函数返回值
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