Linux: The Complete Reference, Sixth Edition
Paperback: 830 pages
Publisher: McGraw-Hill Osborne Media; 6 edition (November 19, 2007)
ISBN-10: 007149247X
Contents at a Glance
Part I Introduction
1 Introduction to Linux . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Adding Fonts
fonts:/ URL in a file manager window
.fonts
/usr/share/fonts
fonts:/System
fc-cache
fc-list | sort
Part II The Linux Shell and File Structure
3 The Shell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
/etc/inputrc
/etc/profile
.inputrc
4 The Shell Scripts and Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
BASH Shell
.bash_profile Login initialization file
.profile Login initialization file (same as .bash_profile)
.bashrc BASH shell configuration file
.bash_logout Logout name
.bash_history History file
/etc/profile System login initialization file
/etc/bashrc System BASH shell configuration file
/etc/profile.d Directory for specialized BASH shell configuration files
5 Shell Con? guration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
6 Linux Files, Directories, and Archives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Part III Desktop
7 The X Window System, Xorg, and Display Managers . . . . . . . . . . . . . . . . . 145
Xorg Directories
/usr/X11R6/lib Suppor ting libraries
/usr/bin Programs (X Window System clients and servers)
/usr/include/X11 Development header files
/usr/share/man/X11 Man pages
/usr/share/X11/doc Documentation
/usr/share/X11 System X11 configuration and suppor t files
/etc/X11 Configuration files
X Window System Configuration Tools
xorgcfg Xorg screen-based X Window System configuration tool
Xorg -configure Xorg X Window System configuration tool that is built into the Xorg X server
xorgconfig Older Xorg configuration tool
Sax2 SUSE X Window System configuration tool
/etc/X11/xorg.conf The X Window System configuration file; edited by the configuration tools
Xorg Configuration: /etc/X11/xorg.conf
X Window System Configuration Files: .xinitrc, .xsession, and .Xresources
X Window System Configuration Files and Directories
.Xmodmap User’s X Window System input devices configuration file
.Xresources User’s X Window System resource configuration file
.Xdefaults User’s X Window System resource configuration file
.xinitrc User’s X Window System configuration file read automatically (b xinit, if it exists)
.Xclients or .Xsessions User’s X Window configuration file
.Xauthority User’s access controls through XDM GUI login inter face
/etc/X11/ Directory that holds X Window System release 6 configuration file and subdirectories
/etc/X11/fs System X Window System fonts configuration directory
/etc/X11/xinit/xinitrc System X Window System initialization file; automatically read bxinit
/etc/X11/xinit/Xclients System X Window System configuration file
/etc/X11/Xresources System X Window System resources file
/etc/X11/Xmodmap System X Window System input devices file
/usr/share/X11/rgb.txt X Window System colors. Each entry has four fields: the first three fields are numbers for red, green, and blue; the last field
is the name given to the color.
/usr/share/X11 System-managed X Window System directory for font storage and application configuration
The XDM Configuration Files and Directories
/etc/X11/xdm XDM configuration directory
xdm-config XDM configuration file
Xsession Star tup script for user session
Xresource Resource features for XDM login window
Xsetup Sets up the login window and XDM login screen
Xstartup Session star tup script
xdm-errors Errors from XDM sessions
.xsession User’s session script in the home directory; usually executed by Xsession
Xreset Resets the X Window System after a session ends
.Xauthority User authorization file where XDM stores keys for clients to read
GDM Configuration: gdmsetup
GDM Configuration Files: /etc/gdm and /usr/share/gdm
GDM Configuration Files and Directories
/etc/gdm GDM configuration directory
/usr/share/gdm GDM configuration directory for default settings and themes
defaults.conf GDM default configuration file, /usr/share/gdm
custom.conf GDM custom configuration file, /etc/gdm
Init Star tup scripts for configuring GDM display
PreSession Scripts execute at star t of session
PostSession Scripts execute when session ends
PostLogin Scripts execute after login
X Window System Command Line Startup: startx, xinit, and xinitrc
8 GNOME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
9 KDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
Part IV Linux Software
10 Software Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
11 Of? ce and Database Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
12 Graphics Tools and Multimedia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255
13 Mail and News Clients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
14 Web, FTP, and Java Clients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281
15 Network Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
Network Information: ping, finger, traceroute, and host
Network Talk and Messenger Clients: VoIP, ICQ, IRC, AIM, and Talk
Part V Security
16 Encryption, Integrity Checks, and Signatures . . . . . . . . . . . . . . . . . . . . . . . . 313
GNU Privacy Guard
GPG Commands and Options
-s, --sign Signs a document, creating a signature. May be combined with --encrypt.
--clearsign Creates a clear-text signature.
-b, --detach-sign Creates a detached signature.
-e, --encrypt Encrypts data. May be combined with --sign.
--decrypt [file] Decrypts file (or stdin if no file is specified) and writ it to stdout (or the file specified with --output). If decrypted file is signed, the signature is verified.
--verify [[sigfile] [signed-files]] Verifies a signed file. The signature can be either contained with the file or a separate detached signature file.
--list-keys [names] Lists all keys from the keyrings or those specified.
--list-public-keys [names] Lists all keys from the public keyrings or those spec
--list-secret-keys [names] Lists your private (secret) keys.
--list-sigs [names] Lists your keys along with any signatures they have
--check-sigs [names] Lists keys and their signatures and verifies the signatures.
--fingerprint [names] Lists fingerprints for specified keys.
--gen-key Generates a new set of private and public keys.
--edit-key name Edits your keys. Commands per form most key operations, such as sign to sign a key or passwd to change your passphrase.
--sign-key name Signs a public key with your private key. Same as sign in --edit-key.
--delete-key name Removes a public key from the public keyring.
--delete-secret-key name Removes private and public keys from both the secret and public keyrings.
--gen-revoke Generates a revocation cer tificate for your own key.
--export [names] Expor ts a specified key from your keyring. With no arguments, expor ts all keys.
--send-keys [names] Expor ts and sends specified keys to a keyserver. The option --keyserver must be used to give the name of this keyserver.
--import [files] Impor ts keys contained in files into your public keyring.
-a, --armor Creates ASCII armored output, ASCII version of encrypted data.
-o, --output file Writes output to a specified file.
--default-key name Specifies the default private key to use for signatures.
--keyserver site Looks up public keys not on your keyring. Can also specify the site to send your public key to. host -l pgp.net | grep will list the keyservers.
-r, --recipient names Encrypts data for the specified user, using that user’s public key.
--default-recipient names Specifies the default recipient to use for encrypting data.
.gnugpg/gpg.conf
Intrusion Detection: Tripwire and AIDE
17 Security-Enhanced Linux . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327
SELinux Tools
seinfo Displays policy statistics.
sestatus Checks status of SELinux on your system, including the contexts of processes and files.
sesearch Searches for Type Enforcement rules in policies.
seaudit Examines SELinux log files.
sediffx Examines SELinux policy differences.
autid2allow Generates policy to allow rules for modules using audit AVC denial messages.
apol The SELinux Policy Analysis tool.
checkpolicy The SELinux policy compiler.
fixfiles Checks file systems and sets security contexts.
restorecon Sets security features for par ticular files.
newrole Assigns new role.
setfiles Sets security context for files.
chcon Changes context.
chsid Changes security ID.
SELinux Policy Configuration Files
assert.te Access vector asser tions
config/appconfig-* Application runtime configuration files
policy/booleans.conf Tunable features
file_contexts Security contexts for files and directories
policy/flask Flask configuration
policy/mcs Multi-Category Security (MCS) configuration
doc Policy documentation suppor t
policy/modules Security policy modules
policy/modules.conf Module list and use
policy/modules/admin Administration modules
policy/modules/apps Application modules
policy/modules/kernel Kernel modules
policy/modules/services Services and server modules
policy/modules/system System modules
policy/rolemap User domain types and roles
policy/users General users definition
config/local.users Your own SELinux users
policy/constraints Additional constraints for role transition and object access
policygentool Script to generate policies
policy/global_tunables Policy tunables for customization
policy/mls Multi-Level Security (MLS) configuration
18 IPsec and Virtual Private Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349
19 Secure Shell and Kerberos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359
SSH Tools
Ssh SSH client
Sshd SSH server (daemon)
Sftp SSH FTP client, Secure File Transfer Program. Version 2 only. Use ? to list sftp commands (SFTP protocol)
sftp-server SSH FTP server. Version 2 only (SFTP protocol)
Scp SSH copy command client
ssh-keygen Utility for generating keys. -h for help
ssh-keyscan Tool to automatically gather public host keys to generate ssh_known_hosts files
ssh-add Adds RSD and DSA identities to the authentication agent
ssh-agent SSH authentication agent that holds private keys for public key authentication (RSA, DSA)
ssh-askpass X Window System utility for querying passwords, invoked by ssh-add (openssh-askpass)
ssh-askpass-gnome GNOME utility for querying passwords, invoked by ssh-add
ssh-signer Signs host-based authentication packets. Version 2 only. Must be suid root (per formed by installation)
Slogin Remote login (version 1)
SSH Configuration Files
$HOME/.ssh/known_hosts Records host keys for all hosts the user has logged in to (that are not in /etc/ssh/ssh_known_hosts).
$HOME/.ssh/random_seed Seeds the random number generator.
$HOME/.ssh/id_rsa Contains the RSA authentication identity of the user.
$HOME/.ssh/ id_dsa Contains the DSA authentication identity of the user.
$HOME/.ssh/id_rsa.pub Contains the RSA public key for authentication. The contents of this file should be added to $HOME/.ssh/authorized_keys on all machines where you want to log in using RSA authentication.
$HOME/.ssh/id_dsa.pub Contains the DSA public key for authentication. The contents of this file should be added to $HOME/.ssh/authorized_keys on all machines where you want to log in using DSA authentication.
$HOME/.ssh/config The per-user configuration file.
$HOME/.ssh/authorized_keys Lists the RSA or DSA keys that can be used for logging in as this user.
/etc/ssh/ssh_known_hosts Contains the systemwide list of known host keys.
/etc/ssh/ssh_config Contains the systemwide configuration file. This file provides defaults for those values not specified in the user’s configuration file.
/etc/ssh/sshd_config Contains the SSH server configuration file.
/etc/ssh/sshrc Contains the system default. Commands in this file are executed by ssh when the user logs in, just before the user’s shell (or command) is star ted.
$HOME/.ssh/rc Contains commands executed by ssh when the user logs in, just before the user’s shell (or command) is star ted.
$cat larisa.pub >> .ssh/authorized_keys
20 Firewalls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373
Modules: /usr/lib/kernel-version/kernel/net/ipv4/netfilter
Part VI Internet and Network Services
21 Managing Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 401
System Files: /etc/rc.d
rc.sysinit the commands for initializing your system, including the mounting and unmounting of your file systems.
and rc.local the last initialization file executed
System Files and Directories
/etc/sysconfig Directory that holds system configuration files and directories.
/etc/rc.d Directory that holds system star tup and shutdown files.
/etc/rc.d/rc.sysinit Initialization file for your system.
/etc/init.d/rc.local Initialization file for your own commands; you can freely edit this file to add your own star tup commands; this is the last star tup file executed.
/etc/init.d Directory that holds network scripts to star t up network connections.
/etc/rc.d/rcnum.d Directories for different runlevels, where num is the runlevel. The directories hold links to scripts in the /etc/init.d directory.
/etc/init.d Directory that holds system service scripts (see Table 21-2).
/etc/init.d/halt Operations per formed each time you shut down the system, such as unmounting file systems; called rc.halt in other distributions.
Service Management: chkconfig, services-admin, rrconf, sysv-rc-conf, and update-rc.d
22 FTP Servers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 423
Files for vsftpd
vsftpd.ftpusers List of users always denied access
vsftpd.user_list Specified users denied access (allowed access if userlist_
deny is NO)
vsftpd.chroot_list List of local users allowed access (denied access if chroot_local_user is on)
/etc/vsftpd/vsftpd.conf vsftpd configuration file (or /etc/vsftpd/vsftpd.conf)
/etc/pam.d/vsftpd PAM vsftpd script
/etc/rc.d/init.d/vsftpd Service vsftpd server script, standalone
/etc/xinetd.d/vsftpd Xinetd vsftpd server script
23 Web Servers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 443
24 Proxy Servers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 467
25 Mail Servers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 477
Sendmail Files and Directories
/etc/mail/sendmail.cf Sendmail configuration file
/etc/mail/sendmail.mc Sendmail M4 macro configuration file
/etc/mail/submit.cf Sendmail configuration file for mail submission mode where Sendmail does not run as a server but merely submits mail
/etc/mail/submit.mc Sendmail M4 macro configuration file for Sendmail mail submission mode
/etc/aliases Sendmail aliases file for mailing lists
/etc/aliases.db Sendmail aliases database file generated by the newaliases command using the aliases file
/etc/mail/access Sendmail access text file; access control for screening or relaying messages from different hosts, networks, or users; used to generate the access.db file
/etc/mail/access.db Sendmail access database file, generated from the access text file
/etc/mail/local-host-names Sendmail localhosts file for multiple hosts using the same mail server (formerly sendmail.cw)
/etc/mail/trusted-users Sendmail trusted users file (formerly sendmail.ct)
/etc/mail/error-header Sendmail error header file (formerly sendmail.oE)
/etc/mail/helpfile Sendmail help file (formerly sendmail.ht)
/etc/mail/statistics Sendmail statistics file (formerly sendmail.st)
/etc/mail/virtusertable Sendmail vir tual user table text file; maps user vir tual domain addresses, allowing vir tual domains to be hosted on one system; make entries in this file and then use it to generate the
virtusertable.db file
/etc/mail/virtusertable.db Sendmail vir tual user table database generated from the virtusertable file
/etc/mail/mailertable Sendmail mailer table text file used to override routing for your domains
/etc/mail/mailertable.db Sendmail mailer table database file, generated from the mailertable
file
/etc/mail/userdb Sendmail user database file
/etc/mail/domaintable Sendmail domaintable file, maps a domain name to another domainame
/etc/mail/domaintable.db Sendmail domaintable database file, generated from the domaintable file
/var/spool/mail Incoming mail
/var/spool/mqueue Outgoing mail
/var/spool/maillog Mail log file
26 Print, News, Search, and Database Servers . . . . . . . . . . . . . . . . . . . . . . . . . . 503
CUPS Configuration Files
classes.conf Contains configurations for different local printer classes
client.conf Lists specific options for specified clients
cupsd.conf Configures the CUPS server, cupsd
printers.conf Contains printer configurations for available local printers
CUPS Administrative Tools
lpadmin CUPS printer configuration
lpoptions Sets printing options
enable Activates a printer
disable Stops a printer
accept Allows a printer to accept new jobs
reject Prevents a printer from accepting print jobs
lpinfo Lists CUPS devices available
MySQL Commands
mysqld MySQL server
mysql MySQL client
mysqladmin Creates and administers databases
mysqldump Database backup
mysqlimport Impor ts text files
mysqlshow Displays databases
Part VII System Administration
27 Basic System Administration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 523
Basic System Administration Tools
su root Logs a superuser into the root from a user login; the superuser returns to the original ogin with a CTRL-D.
sudo command Restricts administrative access to specified users.
passwd login-name Sets a new password for the login name.
telinit runlevel Changes the system runlevels.
shutdown options time Shuts down the system.
date Sets the date and time for the system.
The Linux Auditing System: auditd /etc/auditd.conf
28 Managing Users . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 551
Paths for User Configuration Files
/home The user’s own home directory
/etc/skel The default initialization files for the login shell, such as .bash_profile,.bashrc, and .bash_logout; includes many user setup directories and files such as .kde for KDE and Desktop for GNOME
/etc/shells The login shells, such as BASH or TCSH
/etc/passwd The password for a user
/etc/group The group to which the user belongs
/etc/shadow Encrypted password file
/etc/gshadow Encrypted password file for groups
/etc/login.defs Default login definitions for users
29 File Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 583
30 RAID and LVM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 615
LVM Commands
lvm Open an interactive shell for executing LVM commands
lvmdiskscan Scan all disks for LVM physical par titions
lvdisplay Display detailed information about logical volumes
lvcreate Create logical volumes
lvrename Rename a logical volume
lvchange Modify a logical volume
lvextend Extend the size of a logical volume
lvreduce Reduce the size of a logical volume
lvremove Remove logical volumes
lvs List logical volumes with detailed information
lvresize Change the size of a logical volume
lvscan Scan system for logical volumes
pvdisplay Display detailed information about LVM physical par tition
pvchange Modify an LVM physical par tition
pvcreate Create LVM physical par titions
pvmove Move contnest of an LVM physical par tition to another par tition
pvremove Delete LVM physical par titions
pvs List physical par titions with detailed information
pvresize Resize a physical par tition
pvscan Scan system for physical par titions
vgdisplay Display detailed information about volume groups
vgexport Activate a volume group
vgimport Make an expor ted volume group known to a new system. Useful for moving an activated volume group from one system to another.
vgmerge Combine volume groups
vgreduce Remove physical par titions from a volume group
vgremove Delete a volume group
vgs List volume groups with detailed information
vgslit Split a volume group
vgscan Scan system for volume groups
vgck Check volume groups
vgrename Rename a volume group
vgcfgbackup Backup volume group configuration (metadata)
vgcfgrestore Restore volume group configuration (metadata)
pvcreate /dev/sda1 /dev/sdb1 /dev/sdc1
vgcreate mymedia /dev/sdb1 /dev/sdc1
lvcreate -n myvideo -l 540GB mymedia
lvcreate -n mypics -l 60GB mymedia
vgchange -a y mymedia
mkfs.ext3 myvideo
mkfs.ext3 mypics
mount –t ext3 /dev/mymedia/mypics /mydata/mypics
mount –t ext3 /dev/mymedia/myvideo /mydata/myvideo
31 Devices and Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 639
Device Resources
/etc/sysconfig/hwconf Hardware configuration and listing for your system
/sys The sysfs file system listing configuration information for all the devices on your system
/proc An older process file system listing kernel information, including device information
kernel.org/pub/linux/docs/
device-list/devices.txt Linux device names
/etc/udev The udev configuration directory
/etc/hal The HAL configuration directory
/usr/share/hal/fdi The HAL device information files, for configuring HAL information suppor t and policies
/etc/hal/fdi The HAL system administrator’s device information files
Kernel Module Commands
lsmod Lists modules currently loaded.
insmod Loads a module into the kernel. Does not check for dependencies.
rmmod Unloads a module currently loaded. Does not check for dependencies.
modinfo Displays information about a module: -a (author),-d (description), -p (module parameters), -f (module filename), -v (module version).
depmod Creates a dependency file listing all other modules on which the specified module may rely.
modprobe Loads a module with any dependent modules it may also need. Uses the file of dependency listings generated by epmod: -r (unload a module), -l (list modules).
TIP After making changes to /etc/modprobe.conf or modprobe.d files, you should run depmod again to record any changes in module dependencies.
32 Kernel Administration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 671
33 Backup Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 693
Part VIII Network Administration Services
34 Administering TCP/IP Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 707
TCP/IP Configuration Files
/etc/hosts Associates hostnames with IP addresses, lists domain names for remote hosts with their IP addresses
/etc/host.conf Lists resolver options
/etc/nsswitch.conf Name Switch Service configuration
/etc/resolv.conf Lists domain name server names, IP addresses (name server), and domain names where remote hosts may be located (search)
/etc/protocols Lists protocols available on your system
/etc/services Lists available network services, such as FTP and Telnet, and the por ts they use
Network Interfaces and Routes: ifconfig and route
Monitoring Your Network: ping, netstat, tcpdump, EtherApe, Ettercap, and Wireshark
35 Network Autocon? guration with IPv6, DHCPv6, and DHCP . . . . . . . . . . 745
36 NFS and NIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 761
Network File Systems: NFS and /etc/exports
NFS Daemons
rpc.nfsd Receives NFS requests from remote systems and translates t
requests for the local system.
rpc.mountd Performs requested mount and unmount operations.
rpc.portmapper Maps remote requests to the appropriate NFS daemo
rpc.rquotad Provides user disk quota management.
rpc.statd Provides locking services when a remote host reboots.
rpc.lockd Handles lock recovery for systems that have gone down.
Access to your NFS server can be controlled by the /etc/hosts.allow and /etc/hosts.deny files.
NFS Configuration: /etc/exports
directory-pathname host(options) host(options) host(options)
37 Distributed Network File Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 777
A Where to Obtain Linux Distributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 785
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 787
