7 shell while 读文件

写法1
#!/bin/bash
while read line
do
    echo $line
done < file(待读取的文件)
--------------------------------------------------
写法二：
cat file(待读取的文件) | while read line
do
    echo $line
done
-----------------------------------------------------
写法三：
for line in `cat file(待读取的文件)`
do
    echo $line
done
-----------------------------------------------------
简写：
$ cat file | while read line; do echo $line; done
$ for line in $(<file); do echo $line; done
=== 实践 === 
#! bin/sh
 
#$str='http://images.stylight.de/static/res200/s2870/2870657.1.jpg%0D'
while read line
do
   wget -p ${line:0:59}
done <‘XXX’;

#6 if else
if [ expression ]
then
   XXX
else
   XXX
fi
#5 shell写log
cat >run.sh
exec >XXX.run.log 2>&1
echo Start time:
date


#4 rename“--”
for file in $(find ./ -name "*");do mv $file $(echo "$file"|sed 's/\-\-P5//');done

#0 查看centos系统版本号
cat /etc/redhat-release
#1 读取脚本的绝对路径目录
g_progdir_abs=$(dirname "$(readlink -f "$0")");

#2 提示参数
if [ $# -lt 1 ]; then
    echo "Usage: sh  <ref> <bam> <sample> <output>"
    exit
fi

# 3 写function
name（）{
    echo “${g_prog:=$0}: Error! ""$@" 1>&2;
    exit 1;
}

linux中shell变量@,1,*
所有参数列表。如"1 n"的形式输出所有参数。
@"用「"」括起来的情况、以"2" … "#
添加到Shell的参数个数

# 3 判断空字符串
  if [[ ! -z "${SMRT_IGNORE_CUSTOM_PIPELINES:-}" ]] ; then   -z 空字符串返回为真

# 4 改~家目录环境变量
export HOME=/data/username