SHELL读取文件的方法

 

1、shell判断文件,目录是否存在或者具有权限 

#!/bin/sh 

myPath="/var/log/httpd/" 
myFile="/var /log/httpd/access.log" 

# 这里的-x 参数判断$myPath是否存在并且是否具有可执行权限 
if [ ! -x "$myPath"]; then 
mkdir "$myPath" 
fi 
 
# 这里的-d 参数判断$myPath是否存在 
if [ ! -d "$myPath"]; then 
mkdir "$myPath" 
fi 

# 这里的-f参数判断$myFile是否存在 
if [ ! -f "$myFile" ]; then 
touch "$myFile" 
fi 

# 其他参数还有-n,-n是判断一个变量是否是否有值 
if [ ! -n "$myVar" ]; then 
echo "$myVar is empty" 
exit 0 
fi 

# 两个变量判断是否相等 
if [ "$var1" = "$var2" ]; then 
echo '$var1 eq $var2' 
else 
echo '$var1 not eq $var2' 
fi 

 

-f 和-e的区别 

Conditional Logic on Files 

-a file exists. -b file exists and is a block special file. -c file exists and is a character special file. -d file exists and is a directory. -e file exists (just the same as -a). -f file exists and is a regular file. -g file exists and has its setgid(2) bit set. -G file exists and has the same group ID as this process. -k file exists and has its sticky bit set. -L file exists and is a symbolic link. -n string length is not zero. -o Named option is set on. -O file exists and is owned by the user ID of this process. -p file exists and is a first in, first out (FIFO) special file or named pipe. -r file exists and is readable by the current process. -s file exists and has a size greater than zero. -S file exists and is a socket. -t file descriptor number fildes is open and associated with a terminal device. -u file exists and has its setuid(2) bit set. -w file exists and is writable by the current process. -x file exists and is executable by the current process. -z string length is zero. 是用 -s 还是用 -f 这个区别是很大的！

 

 

2、 SHELL读取文件的方法

#使用read命令读取一行数据
while read myline
do
echo "LINE:"$myline
done < datafile.txt

#使用read命令读取一行数据
cat datafile.txt | while read myline
do 
echo "LINE:"$myline
done

#读取一行数据，若多行则读取每一行数据
cat datafile.txt | while myline=$(line)
do 
echo "LINE:"$myline
done

备注：此种方式已验证没有问题。

#读取一行数据
while myline=$(line)
do 
echo "LINE:"$myline
done < datafile.txt

#使用read命令读取变量数据
cat datafile.txt | while read paraa parab parac
do
echo "PARAA:"$paraa
echo "PARAB:"$parab
echo "PARAC:"$parac
done

#使用read命令读取变量数据
while read paraa parab parac
do
echo "PARAA:"$paraa
echo "PARAB:"$parab
echo "PARAC:"$parac
done < datafile.txt

 

3、使用

通过对文件的判断与读取，可实现读取一个文件中每行数据，进而实现对每行数据进一步处理。

实例：

1) 获取某程序所有已打开的pid，将pid打印出来，或关闭此进程。

a.sh文件，批量执行日志文件打印操作

#!/bin/bash
time=$(date +%F-%H-%M)
echo "$time------start--------"

res_dir=/home/weblogic/domains/scmsDomain4500/log
to_dir=/tmp/201601

echo "开始执行命令"
cd $res_dir
pwd
tail -f ManagedServer9802.out>$to_dir/9802_$time.log &
tail -f ManagedServer9803.out>$to_dir/9803_$time.log &
tail -f ManagedServer9804.out>$to_dir/9804_$time.log &

echo "命令执行结束"

 

b.sh文件，批量停止tail -f 的命令

#!/bin/bash

dir="/tmp/201601/"
cd $dir

echo "打印当前tail的进程数"
ps -ef|grep tail|grep -v "grep"|awk -F " " '{print $2}'|wc -l

echo "将tail进程号保存到一个文件中"
ps -ef|grep tail|grep -v "grep"|awk -F " " '{print $2}'>$dir/data.log


echo "打印该文件"
more data.log

echo "开始执行命令"

if [ ! -f "$data.log" ]; then

cat data.log|while myline=$(line)

do

echo $myline
echo “删除该进程”
kill -9 $myline

done
fi

echo "删除该文件"
rm -f data.log

echo "命令执行结束"