LPI Linux Certification in a Nutshell (11 page)

rpm

rpm
-i
[
options
]
(also rpm --install)
rpm
-U
[
options
] (also rpm --upgrade)
rpm
-e
[
options
] (also rpm --uninstall)
rpm
-q
[
options
] (also rpm --query)
rpm
-V
[
options
] (also rpm --verify)

The
install mode
(
rpm
-i
) is used to install new packages. A variant of install
mode is the
upgrade mode
(
rpm
-U
), where an installed package is upgraded to a more
recent version. Another variant is the
freshen mode
(
rpm
-F
), which upgrades only packages that have an older
version already installed on the system. But
rpm
’s
-F
option has
limited value, since it doesn’t handle
dependency
changes at all. In other
words, if a new version of a package requires that another package
be installed,
-F
won’t automatically install
the new package, even if it is listed on the command line.

To install a new package, simply use the
rpm
-i
command with the name of a package file. If the new
package depends upon another package, the install fails, like
this:

#
rpm -i gcc-2.96-113.i386.rpm
error: failed dependencies:
binutils >= 2.11.93.0.2-6 is needed by gcc-2.96-113
cpp = 2.96-113 is needed by gcc-2.96-113
glibc-devel is needed by gcc-2.96-113

To correct the problem, the dependency must first be
satisfied. In this example,
gcc
is dependent on
binutils, cpp
, and
glibc-devel
, which all must be installed first
(or at the same time, as in this example):

#
rpm -i binutils-2.11.93.0.2-11.i386.rpm cpp-2.96-113.i386.rpm \
glibc-devel-2.2.5-44.i386.rpm gcc-2.96-113.i386.rpm

Upgrading an existing package to a newer version can be done
with the
-U
option. Upgrade mode is really a
special case of the install mode, where existing packages can be
superseded by newer versions. Using
-U
, a
package can be installed even if it doesn’t already exist, in which
case it behaves just like
-i
:

#
rpm -U gcc-2.96-113.i386.rpm

This mode is used to remove installed packages from
the system. By default,
rpm
uninstalls a
package only if no other packages depend on it.

Package removal is the opposite of installation and has the
same dependency constraints:

#
rpm -e glibc-devel
error: removing these packages would break dependencies:
glibc-devel is needed by gcc-2.96-113

Installed packages and raw package files can be
queried using the
rpm -q
command. Query mode
options exist for package and information selection.

To determine the version of the software contained in an RPM
file, use the query and package information options:

#
rpm -qpi openssh-3.4p1-2.i386.rpm | grep Version
Version     : 3.4p1                Vendor: Red Hat, Inc.

For installed packages, omit the
-p
option and specify a package name instead of a package filename.
Notice if you have multiple versions of the same package installed,
you will get output for all of the packages:

#
rpm -qi kernel-source | grep Version
Version     : 2.4.9                             Vendor: Red Hat, Inc.
Version     : 2.4.18                            Vendor: Red Hat, Inc.
Version     : 2.4.18                            Vendor: Red Hat, Inc.

List the files contained in a package:

#
rpm -qlp gnucash-1.3.0-1.i386.rpm
/usr/bin/gnc-prices
/usr/bin/gnucash
/usr/bin/gnucash.gnome
/usr/doc/gnucash
/usr/doc/gnucash/CHANGES
(...output continues ...)

For an installed package, enter query mode and use the
-l
option along with the package name:

#
rpm -ql kernel-source
/usr/src/linux-2.4.18-14
/usr/src/linux-2.4.18-14/COPYING
/usr/src/linux-2.4.18-14/CREDITS
/usr/src/linux-2.4.18-14/Documentation
/usr/src/linux-2.4.18-14/Documentation/00-INDEX
/usr/src/linux-2.4.18-14/Documentation/BUG-HUNTING
/usr/src/linux-2.4.18-14/Documentation/Changes
(...output continues ...)

List the documentation files in a package:

#
rpm -qd at
/usr/doc/at-3.1.7/ChangeLog
/usr/doc/at-3.1.7/Copyright
/usr/doc/at-3.1.7/Problems
/usr/doc/at-3.1.7/README
/usr/doc/at-3.1.7/timespec
/usr/man/man1/at.1
/usr/man/man1/atq.1
/usr/man/man1/atrm.1
/usr/man/man1/batch.1
/usr/man/man8/atd.8
/usr/man/man8/atrun.8

Use
-p
for package filenames.

List configuration files or scripts in a package:

#
rpm -qc at
/etc/at.deny
/etc/rc.d/init.d/atd

Determine what package a particular file was installed from.
Of course, not all files originate from packages:

#
rpm -qf /etc/fstab
file /etc/fstab is not owned by any package

Those that are package members look like this:

#
rpm -qf /etc/aliases
sendmail-8.11.6-15

List the packages that have been installed on the
system:

#
rpm -qa
(... hundreds of packages are listed ...)

To search for a subset with
kernel
in the name, pipe the previous
command to
grep
:

#
rpm -qa | grep kernel
kernel-source-2.4.18-24.7.x
kernel-pcmcia-cs-3.1.27-18
kernel-utils-2.4-7.4
kernel-doc-2.4.18-24.7.x
kernel-2.4.18-24.7.x

Files from installed packages can be compared against
their expected configuration from the RPM database by using
rpm -V
.

Objective 1: Work on the Command Line

This Objective states that a candidate should be able to
interact with shells and commands using the command line. This
includes using single shell commands and one-line command sequences to
perform basic tasks on the command line, using and modifying the shell
environment, including defining, referencing, and exporting
environment variables, using and editing command history, and invoking
commands inside and outside the defined path. Weight: 4.

Objective 2: Process Text Streams Using
Filters

This Objective states that a candidate should be able to
apply filters to text streams. Tasks include sending text files and
output streams through text utility filters to modify the output, and
using standard Unix commands found in the GNU
coreutils
package. Weight: 3.

Objective 3: Perform Basic File
Management

This Objective states that candidates should be able to
use the basic Linux commands to copy, move, and remove files and
directories. Tasks include advanced file management operations such as
copying multiple files recursively, removing directories recursively,
and moving files that meet a wildcard pattern. The latter task
includes using simple and advanced wildcard specifications to refer to
files, as well as using
find
to locate and act on
files based on type, size, or time. This also includes usage of the
commands
tar, cpio
, and
dd
for archival purposes. Weight: 4.

Objective 4: Use Streams, Pipes, and
Redirects

This Objective states that a candidate should be able to
redirect streams and connect them to efficiently process textual data.
Tasks include redirecting standard input, standard output, and
standard error, piping the output of one command to the input of
another command, using the output of one command as arguments to
another command, and sending output to both
stdout
and a file. Weight: 4.

Objective 5: Create, Monitor, and Kill
Processes

This Objective states that a candidate should be able to
manage processes. This includes knowing how to run jobs in the
foreground and background, bring a job from the background to the
foreground and vice versa, start a process that will run without being
connected to a terminal, and signal a program to continue running
after logout. Tasks also include monitoring active processes,
selecting
and sorting processes for
display, sending signals to processes, and killing processes. Weight:
4.

Objective 6: Modify Process Execution
Priorities

This Objective states that a candidate should be able to
manage process execution priorities. The tasks include running a
program with higher or lower priority, determining the priority of a
process, and changing the priority of a running process. Weight:
2.

Objective 7: Search Text Files Using Regular
Expressions

This Objective states that a candidate should be able to
manipulate files and text data using regular expressions. This
includes creating simple regular expressions containing several
notational elements, as well as using regular
expression
tools to perform searches
through a filesystem or file content.
Weight: 2
.

Objective 8: Perform Basic File Editing Operations Using
vi

This Objective states a candidate should be able to edit
files using
vi
. This includes
vi
navigation, basic
vi
modes, and inserting, editing, deleting, copying, and finding text.
Weight: 3.

Every computer system requires a human interface component.
For Linux system administration, a text interface is typically used. The
system presents the administrator with a
prompt
, which at its simplest is a
single character such as
$
or
#
. The prompt signifies
that the system is ready to accept typed commands, which usually occupy
one or more lines of text. This interface is generically called the
command line
.

It is the job of a program called a
shell
to
provide the command prompt and to interpret commands. The shell provides
an interface layer between the Linux kernel and the end user, which is how
it gets its name. The original shell for Unix systems was written by
Stephen Bourne and was called simply
sh
. The default Linux shell is
bash
, the
Bourne-Again
Shell
, which is a GNU variant of
sh
. This
chapter will not cover all aspects of the
bash
shell.
At this point, we are primarily concerned with our interaction with
bash
and the effective use of commands.

$
echo $PS1
\$

[\u@\h \W]\$

[adam@linuxpc adam]$

$
export MYVAR

$
echo $MYVAR

$
MYVAR="hello"
$
echo $MYVAR
hello

$
bash
$
echo $MYVAR

$
exit
$
export MYVAR
$
bash
$
echo $MYVAR
hello

$
set –o vi

$
set –o allexport

$
ls

$
ls -l

$
ls -l -a
$
ls -la

$
ls -l --all

$
ls -l *.c

$
ls --all *.c -l

$
sort name_list
$
sort –k 2 name_list