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10.2.4 Man Pages

For some GNU applications (such as tar) the man pages are no longer

maintained. For these commands, use the --help option to get a quick

overview or the info pages, which provide more in-depth instructions. info

is GNU’s hypertext system. Read an introduction to this system by entering

info info. Info pages can be viewed with Emacs by entering emacs -f

info or directly in a console with info. You can also use tkinfo, xinfo, or

the SUSE help system to view info pages.

10.2.5 The Command ulimit

With the ulimit (user limits) command, it is possible to set limits for the

use of system resources and to have these displayed. ulimit is especially

useful for limiting the memory available for applications. With this, an ap-

plication can be prevented from using too much memory on its own, which

could bring the system to a standstill.

ulimit can be used with various options. To limit memory usage, use the

options listed in Table 10.1.

Table 10.1: ulimit: Setting Resources for the User

-m maximum size of physical memory

-v maximum size of virtual memory

-s maximum size of the stack

-c maximum size of the core ﬁles

-a display of limits set

System-wide settings can be made in /etc/profile. There, enable cre-

ation of core ﬁles, needed by programmers for debugging. A normal user

cannot increase the values speciﬁed in /etc/profile by the system ad-

ministrator, but he can make special entries in his own~/.bashrc.

Example 10.3: ulimit: Settings in /.bashrc

# Limits of physical memory:

ulimit -m 98304

# Limits of virtual memory:

ulimit -v 98304

248 10.2. Hints on Special Software Packages