Basic Unix Commands

Some commands were practiced in the lab. So since this is just for future brush up during interviews it will have only extra features, basic features I have to try and remember.

Very effective:

• chmod - changes permission for directories/files. eg: chmod ugo+r+w+x filename - gives u-user,g-group,o-others the permission to read(r),write(w) and execute(x). For directory, execute permission is required.
• ls - list files in the directory. The options most commonly used are -l which is to print file list with permissions, time modified, user details and the other option -a prints all files including the . and .. directories.
• ff - find files. This command is used to search for a file throughout all available directories.
  
• diff - The command which is really unique to unix. This command compares the two files and prints the differences with line numbers.
  
• | - pipe. This allows commands to be combined.

Very Basic:

• cp - copy command. This copies file from one location/one name to other location/another name.
• mv - move command. This moves/changes file location or name respectively. One had to be careful, 'cause this results in deletion of the original file.
• cd - change directory. When typed with no argument, it takes to home directory.
• pwd - current working directory.
  
• wc - word count. The order is lines,words and characters.
• gzip & gunzip - compression/decompression of files.
• finger - cmd to print details about user. Finger protocol (network).
• telnet, ftp, rlogin - used for connecting to outer hosts.
• kill - kills process forcibly
• ps - lists the process run by you.
• du - prints disk usuage.