Linux Tips

1. tar decompress (解压缩) problem: "operation not permitted"

• Donot put the file to be decompressed in the folder in XP System or in the folder shared with XP Sytem. Move the file to the folder in the Linux system, and decompress it. Linux文件系统类型一般采用ext2，而Win32的文件类型一般是Fat32或ntfs，它们对文件的存储和组织方式是不同的，甚至文件的属性信息也是不同的。当你把一个原先在ext2文件系统上的gz文件解压缩到fat32文件系统上时，就会出现如上的提示信息，常见的提示信息还有： Cannot change ownership to uid 500, gid 100: Operation not permitted。 如果你在非fat32分区下(如ext2)解压缩这个文件，应该不会出现你所说的提示信息了。

2. cd command: "Bash...No such file or directory"

• cd followed with full pathes of the folder, such as "home/..../..."

3. Install G++ in ubuntu

• 首先确定你已经联网而且插入ununtu安装或者安装包，
• 然后在终端里面执行
• sudo apt-get install build-essential
• 输入root的密码后回车

4. "missing: libstdc++.so.5", install 安装

• sudo apt-get install libstdc++5

5. Check CPU information

• cat /proc/cpuinfo

6. how to check linux kernel is 32 bit or 64 bit

• Usually it is in the name of the kernel.
  
  
  Code:

  >$ uname -m
  x86_64

  Tells me I am running a 64bit kernel or check a binary file on the system if it is 64bit good chance you are running 64bit.
  
  
  Code:

  >$ file /usr/bin/file
  /usr/bin/file: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), for GNU/Linux 2.6.8,

7. Search a file in Linux

• $ find / -name 'program.c' 2>/dev/null
  $ find / -name 'program.c' 2>errors.txt
  

  /		Start searching from the root directory (i.e / directory)
  -name		Given search text is the filename rather than any other attribute of a file
  'program.c'		Search text that we have entered. Always enclose the filename in single quotes.. why to do this is complex.. so simply do so.

  Note : 2>/dev/null is not related to find tool as such. 2 indicates the error stream in Linux, and /dev/null is the device where anything you send simply disappears. So 2>/dev/null in this case means that while finding for the files, in case any error messages pop up simply send them to /dev/null i.e. simply discard all error messages.

• $ find /home/david -name 'index*'
  $ find /home/david -iname 'index*'
  The 1st command would find files having the letters index as the beginning of the file name. The search would be started in the directory /home/david and carry on within that directory and its subdirectories only.
  The 2nd command would search for the same, but the case of the filename wouldn't be considered. So all files starting with any combination of letters in upper and lower case such as INDEX or indEX or index would be returned.
  
  -
  
  $ find -name met*
  The above command would start searching for the files that begin with the letters 'met' within the current directory and the directories that are present within the current directory. Since the directory is not specified as the the second parameter, Linux defaults to using the current directory as the one to start the search in.
  
  -
  
  $ find /mp3collection -name '*.mp3' -size -5000k
  $ find / -size +10000k
  The 1st command would find within a directory called /mp3collection, only those mp3 files that have a size less than 5000 Kilobytes ( <> 10MB)
  
  -
  
  $ find /home/david -amin -10 -name '*.c'
  $ find /home/david -atime -2 -name '*.c'
  $ find /home/david -mmin -10 -name '*.c'
  $ find /home/david -mtime -2 -name '*.c'
  
  The 1st commmand searches for those files that are present in the directory /home/david and its subdirectoires which end in .c and which have been accessed in the last 10 minutes.
  The 2nd command does the same but searches for those files that have been accessed in the last 10 hours.
  The 3rd and the 4th commands do the same as the 1st and 2nd commands but they search for modified files rather than accessed files. Only if the contents of the files have been modified, would their names be returned in the search results.
  
  -
  
  $ find / -mount -name 'win*'
  This command searches for files starting with the letters 'win' in their filenames. The only difference is that the mounted filesystems would not be searched for this time. This is useful when you have your Windows partitions mounted by default. And a search for 'win' might return many files on those partitions, which you may not be really interested in. This is only one use of -mount parameter.
  
  -
  
  $ find /mp3-collection -name 'Metallica*' -and -size +10000k
  $ find /mp3-collection -size +10000k ! -name "Metallica*"
  $ find /mp3-collection -name 'Metallica*' -or -size +10000k
  Boolean operators such as AND, OR and NOT make find an extremely useful tool.
  The 1st command searches within the directory /mp3-collection for files that have their names beginning with 'Metallica' and whose size is greater than 10000 kilobytes (> 10 MB).
  The 2nd command searches in the same directory as above case but only for files that are greater than 10MB, but they should not have 'Metallica' as the starting of their filenames.
  The 3rd command searches in the same directory for files that begin with 'Metallica' in their names or all the files that are greater than 10 MB in size.
  
  -
  
  The exec option is probably the most important feature of the find tool. The exec command allows you to execute a particular command on the results of the find command. A simple demonstration of this feature is shown below. Its upto your imagination to make maximum use of this feature. Suppose you wanted to see the details of the files (read, write, execute permission, file size, owner etc..) that have been returned as a search result you could do the following
  
  $ find / - name 'Metallica*' -exec ls -l {\}\ \;
  
  This command would find all the files on your system that begin with the letters 'Metallica' and would then execute the 'ls -l' command on these files. So basically you would be able to see the details of the files that were returned according to your search criteria.
  
  The words following the -exec option is the command that you want to execute i.e. ls -l in this case.
  {\}\ is basically an indicator that the filenames returned by the search should be substituted here.
  \; is the terminating string, and is required at the end of the command

8.
How to install libstdc++.so.5

---

• Search for stdc++5 in synaptic package manager (System->Administration->Synaptic) and then mark and install it. Or use this console command:

• sudo apt-get install libstdc++5

9. Enter as root
First, open a Terminal window and become root:

• sudo bash

(type your user password)

At this point, you should have a root shell. Test this with command

• 'whoami' which should return "root"

1. How do I install .deb packages?

• $ sudo dpkg -i package.deb