General Linux Commands
Just a small collection of commands that I will add to as I find them.....
Getting around + File commands
cd - changes to your home directory rm -rf - removes a directory without prompting. ==USE WITH CAUTION!!!!!!== cd /home/someguy - changes directory to /home/someguy cd .. - moves up one directory pwd - shows the current directory your in mkdir somedir - creates a new directory call somedir ls - lists the directory and files. ls -al shows hidden files and shows the permissions on the listed files too cp one two - copies file one to file two mv one two - renames one to two and obviosuly moves it if another directory is specified. touch somefile - creates a file called somefile vi somefile - opens somefile with the vi editor cat somefile - outputs the contents of somefile into the shell tail somefile - outputs the last 10 lines of somefile by default -n changes this where n is the number of lines required. tail -f somefile I have found very useful too, it shows the contents of a file as it grows. Handy for log files and seeing whats going on. ln -s file linkedfile - creates a symbolic link from file to linkedfile. E.g when installing the flash plugin for FF. wget http://somehost/somefile - Will download somefile to the local machine. http is only used as an example! rm -r dir - Removes a directory while prompting rm somefile - removes somefile while prompting
scp somefile user@somehost:/somedir/dir - will copy somefile from the local machine to somehost using user and to the location specified. Prompts for password if required. ssh -p $ user@somehost - connect to somehost on port '$' as user ssh-copy-id user@somehost - adds the local systems key for user on somehost so you can login without password prompting in future. The command doesnt seem to allow for the use of a non default port(22) as far as I can see :( It may be required to run ssh-keygen before this command. ssh-keygen - generates a public/private key pair for ssh
chmod OCTAL 'file or directory' - Changes the permissions on the file or directory with the supplied OCTAL. The permissions are split into three categories owner, group and world. The three octal digits are ordered like that ie digit one is the owners permissions, digit two the group and digit three worlds. The permissions you want to set can be summarized as a single digit by adding the sum of the values shown below.
- READ - 4 (r)
- WRITE - 2 (w)
- EXECUTE - 1 (x)
gzip somefile - Compress somefile with gzip and rename it to somefile.gz tar czf somefile.tar.gz files - Create a tar called somefile.tar.gz containing the files named and use Gzip compression tar cjf somefile.tar.bz2 files - Create a tar called somefile.tar.bz2 containing the files named and use Bzip2
tar cjf somefile.tar.bz2 - Extract a tar called somefile.tar.bz2 with Bzip2 tar xf somefile.tar - Extract the somefile.tar gzip -d somefile.gz - Extract files from somefile.gz unzip somefile.zip - Extract files from somefile.zip
whois somedomain - Gets the whois info and displays it to the shell. dig somedomain - Gets the dns info and displays it to the shell. -x can be used to reverse lookups netstat -a - lists all listening/active ports. netstat -a | grep tftp - will output all the ports if any tftp is using. Usefull to see if a program is running etc traceroute somehost - Performs a trace route.....
yum install somepackage - Gets somepackage and installs is yum clean all - Cleans yum up if you're having problems has been useful after yum crashed. ps -A - Shows all processes currently running top - shows a task manager type output. free - shows memory and swap usage date - displays the date and time cal - shows this months clander uptime - shows uptime.... man somecommand - shows the manual for somecommand df - shows disk usage du - shows directory usage finger someuser - Shows info about someuser kill pid - kills the selected process -9 might be required sometimes killall someprocess - kills all processes name someprocess history - shows a list of your past commands service someservice status - will make someservice into the staus selected eg. service httpd start would start apache. if you enter the command without selecting a status it will list the available ones for that service. chkconfig someservice status - makes someservice start (or not) on boot e.g chkconfig postfix on would start postfix with every boot.