面试题总结之Linux/Shell

Posted 2020-07-20 浩然

Linux

 

Linux cshrc文件作用

Linux如何起进程/查看进程/杀进程

Linux 文件755 代表什么权限

Linux辅助线程

Linux进程间通信方法

　　pipeline，msgq...

　　进程间通信_百度百科

　　　　http://baike.baidu.com/link?url=tLNXNQvG5Wo6NptnjkflYaUQbdqW5fC3n40Cv4iF4YSX5EzgfJgwIbZnAfpXLVV1QRvP1293Dgo9qRBmSVfME_

 

Shell

 

What is $*?
　　Will display all the commandline arguments that are passed to the script

What is the difference between a shell variable that is exported and the one that is not exported?
　　export LANG=C
　　will make the variable LANG the global variable, put it into the global environment. all other processes can use it.
　　LANG=C
　　will change the value only in the current script.

How will you list only the empty lines in a file (using grep)?
　　grep "^[ ]*$" filename.txt
　　In character set (between [ and ] one space and tab is given)
　　this command will gives all the blank line including those having space and tabs (if pressed)only

How do you read arguments in a shell program - $1, $2 ?
　　#!/bin/sh
　　for i in $*
　　do
　　echo $i
　　done
　　On executig the above script with any number of command-line arguments it will display all the parametsrs.

How would you get the character positions 10-20 from a text file?
　　cut -c10-20 <filename.txt>
　　or
　　cat filename.txt | cut -c 10-20