Linux Command 1

Starting & Stopping
--------------------------------------------------------
shutdown -h now
-> Shutdown the system now and do not reboot

halt
-> Stop all processes - same as above

shutdown -r 5
-> Shutdown the system in 5 minutes and reboot

shutdown -r now
-> Shutdown the system now and reboot

reboot
-> Stop all processes and then reboot - same as above

startx
-> Start the X system


Finding files and text within files
--------------------------------------------------------
find / -name fname
-> Starting with the root directory, look for the file called fname

find / -name ”*fname*”
-> Starting with the root directory, look for the file containing the string fname

locate missingfilename
-> Find a file called missingfilename using the locate command - this assumes you have already used the command updatedb (see next)

updatedb
-> Create or update the database of files on all file systems attached to the linux root directory

which missingfilename
-> Show the subdirectory containing the executable file called missingfilename

grep textstringtofind /dir
-> Starting with the directory called dir , look for and list all files containing textstringtofind

The X Window System
------------------------------------------------------
xvidtune
-> Run the X graphics tuning utility

XF86Setup
-> Run the X configuration menu with automatic probing of graphics cards

Xconfigurator
-> Run another X configuration menu with automatic probing of graphics cards

xf86config
-> Run a text based X configuration menu


Moving, copying, deleting & viewing files
-----------------------------------------------------

ls -l
-> List files in current directory using long format

ls -F
-> List files in current directory and indicate the file type

ls -laC
-> List all files in current directory in long format and display in columns

rm name
-> Remove a file or directory called name

rm -rf name
-> Kill off an entire directory and all it’s includes files and subdirectories

cp filename/home/dirname
->Copy the file called filename to the /home/dirname directory

mv filename /home/dirname
-> Move the file called filename to the /home/dirname directory

cat filetoview
->Display the file called filetoview

man -k keyword
->Display man pages containing keyword

more filetoview
-> Display the file called filetoview one page at a time, proceed to next page using the spacebar

head filetoview
-> Display the first 10 lines of the file called filetoview

head -20 filetoview
->Display the first 20 lines of the file called filetoview

tail filetoview
->Display the last 10 lines of the file called filetoview

tail -20 filetoview
-> Display the last 20 lines of the file called filetoview


Little known tips and tricks
-------------------------------------------
ifconfig
-> List ip addresses for all devices on the machine

apropos subject
-> List manual pages for subject

usermount
-> Executes graphical application for mounting and unmounting file systems

/sbin/e2fsck hda5
->Execute the filesystem check utility on partition hda5

fdformat /dev/fd0H1440
-> Format the floppy disk in device fd0

tar -cMf /dev/fd0
-> Backup the contents of the current directory and subdirectories to multiple floppy disks

tail -f /var/log/messages
-> Display the last 10 lines of the system log.

cat /var/log/dmesg
-> Display the file containing the boot time messages - useful for locating problems. Alternatively, use the dmesg command.

*
-> wildcard - represents everything. eg. cp from/* to will copy all files in the from directory to the to directory

?
-> Single character wildcard. eg. cp config.? /configs will copy all files beginning with the name config. in the current directory to the directory named configs.

[xyz]
-> Choice of character wildcards. eg. ls [xyz]* will list all files in the current directory starting with the letter x, y, or z.

linux single
-> At the lilo prompt, start in single user mode. This is useful if you have forgotten your password. Boot in single user mode, then run the passwd command.

ps
-> List current processes

kill 123
-> Kill a specific process eg. kill 123


Configuration files and what they do
----------------------------------------------
/etc/profile
-> System wide environment variables for all users.

/etc/fstab
-> List of devices and their associated mount points. Edit this file to add cdroms, DOS partitions and floppy drives at startup.

/etc/motd
-> Message of the day broadcast to all users at login.

etc/rc.d/rc.local
-> Bash script that is executed at the end of login process. Similar to autoexec.bat in DOS.

/etc/HOSTNAME
->Contains full hostname including domain.

/etc/cron.*
->There are 4 directories that automatically execute all scripts within the directory at intervals of hour, day, week or month.

/etc/hosts
->A list of all know host names and IP addresses on the machine.

/etc/httpd/conf
->Paramters for the Apache web server

/etc/inittab
->Specifies the run level that the machine should boot into.

/etc/resolv.conf
-> Defines IP addresses of DNS servers.

/etc/smb.conf
->Configure file for the SAMBA server. Allows file and print sharing with Microsoft clients.

/etc/X11/XF86Config
-> Configure file for X-Windows.

~/.xinitrc
-> Defines the windows manager loaded by X. ~ refers to user’s home directory.