Hard Disk

PCI devices

System Calls

Logs

Directory Structure

• directory structure

redirection

• combine stderr with stdout: (cvs update -d 2>&1) | grep -v '^cvs update: Updating'
• >> operator
  • append redirection operator
  • for example cat fileA >> fileB
  • This will copy the contents of fileA and place them at the end of fileB
  • useful commands
• send both stderr and stdout to file: command 1>/dev/null 2>&1

Using ls to only list directories:

• use ls -d */
• in the -d causes the command to list only the directory, not its contents
• the */ lists any file that ends in '/', which are directories

finding files

• 3 Ways

Recursive Touch

• find . -print0 | xargs -r0 touch
• find /home -exec touch {} \;

creating tar/zip file

• Example: tar -cvzf zipped_file_name.tar.gz files_and_or_dir

Shells

• chsh change shell
• echo $0 get current shell
• A7) How can I make bash my login shell?
• passwd -[se]
• make sure pathname appears in /etc/shells

diff

• normal options: -uprN

• -p  --show-c-function
  	Show which C function each change is in.
  

• -D NAME  --ifdef=NAME
  	Output merged file to show `#ifdef NAME' diffs.
  

  example
• example: diff -uprN linux-2.6.25.5-old/ linux-2.6.25.5-new/

cut

• cut -d'#' -f1-1 test - remove '#' comments from the test file

sed

• output only particular lines
• sed -e 'begin_line,end_line!d'
• one-liners

user accounts

• adding
  • useradd -m -G users john
• removing
  • userdel user_to_delete
  • -r can be used to also remove the user's home directory
  • ref

patches

• creating
  • diff -uprN file.orig file
  • p - shows C function

users

• listing
  • cat /etc/passwd | cut -d":" -f1
• add user to a group
  • usermod -aG GROUP1[,GROUP2,...[,GROUPN]]] username
• remove a user
  • userdel -r roger
  • -r - remove home diretory also

Useful Links

• Unix Timeline