8/12/2019 Manejo de Librera Solaris 11

1/4

MANEJO DE LIBRERA SOLARIS 11

Managing Library Paths with crleBySandra Henry-Stocker,ITworld.com | Hardware

Add a comment

April 13, 2005, 8:53 AMDefinitely NOT one of the first dozen Unix commands that

a person learns, the crle command is so infrequently discussed in the hallways of

software development companies that even I don't know how to pronounce it. Is it "see

are elle ee" (phonetically "si ar el i") or am I supposed to say "curly"? After all, Unix

offers few clues in such matters. We have the likes of vi ("vee eye" and awk (which

rhymes with "talk") as two of many examples illustrating that there is no general

pronunciation rule that governs our favorite OS. But, fortunately, since I don't have toread this column to you, let's move on to the more important issue -- what does this

command do and how can you use it in managing your systems?

To begin with, crle stands for "configure runtime linking environment". It is a command

that allows Solaris sysadmins to better manage their dynamic linker. Specifically, it

allows you to configure library paths so that programs run on a system will have as

easy access to shared library files in locations like /usr/local/lib or /opt/lib as they do to

/usr/lib. Instead of configuring a LD_LIBRARY_PATH to give these lib directories

visibility, you run the crle command and augment the load library path on a system-

wide basis. In other words, the crle command is basically the equivalent of updating

ld.config.

What's Configured Now?

To view the system library path on a Solaris system, you can issue the crle command

on a line by itself:

# crle

Default configuration file (/var/ld/ld.config) not found

Default Library Path (ELF): /usr/lib (system default)

Trusted Directories (ELF): /usr/lib/secure (system default)

Notice that, in the absence of an ld.config file, a limited library search path is

established containing only /usr/lib for normal usage.

http://www.itworld.com/sandra-henry-stockerhttp://www.itworld.com/sandra-henry-stockerhttp://www.itworld.com/sandra-henry-stockerhttp://www.itworld.com/hardwarehttp://www.itworld.com/hardwarehttp://www.itworld.com/nls_unixcrle050413#disqus_threadhttp://www.itworld.com/nls_unixcrle050413#disqus_threadhttp://www.itworld.com/nls_unixcrle050413#disqus_threadhttp://www.itworld.com/hardwarehttp://www.itworld.com/sandra-henry-stocker

8/12/2019 Manejo de Librera Solaris 11

2/4

This library path setting is independent of any paths you may have added to your

LD_LIBRARY_PATH interactively or through settings in your dot files. The paths

shown are the paths that binaries on your system will use regardless of the

LD_LIBRARY_PATH setting.

How to Configure New Paths

To add a new path to your dynamic linker, you would use the crle -l command, but this

command overwrites the existing path. In other words, you need to repeat the existing

path elements so as not to remove them. For example, you might type the following

command to add /usr/local/lib to what is shown above:

# crle -l /usr/lib:/usr/local/lib

Afterwards, you should verify the new settings:

# crle

Configuration file [2]: /var/ld/ld.config

Default Library Path (ELF): /usr/lib:/usr/local/lib

Trusted Directories (ELF): /usr/lib/secure (system default)

Command line:

crle -c /var/ld/ld.config -l /usr/lib:/usr/local/lib

What should you do if You Break It?

If you type your crle command carefully, you should have an easy time augmenting

your dynamic loader's search path. If, on the other hand, you break the path -- for

example, by typing crle -l followed only by the paths you intend to add -- you can send

your Solaris system into a very troublesome state. The reason is simple; just about

every command that you type on your Unix system depends on shared object files

stored in /usr/lib -- including commands as benign as ls. So, if /usr/lib disappears from

your linker's search path, your ability to work wonders on the command line will come

to an abrupt end -- at least until you type the command again. The breakage will be

illustrated with errors such as this:

$ ls

ld.so.1: ls: fatal: libc.so.1: open failed: No such file or directory

Killed

8/12/2019 Manejo de Librera Solaris 11

3/4

Normal Unix command functionality can be restored by typing a second crle command.

While you could also fix the problem for yourself by setting your LD_LIBRARY_PATH

as shown below, this wouldn't help anyone else who logs into the system.

LD_LIBRARY_PATH=/lib:/usr/lib;export LD_LIBRARY_PATH

Typing the crle command with the complete library path should fix the problem

immediately and easily -- except when you can't issue it.

What should you do if You Break It with sudo?

A second crle won't help you out of the pit that you inadvertently created if your super

powers are bequeathed through sudo. In this case, you won't be able to reproduce the

linker's path with a "sudo crle" command because sudo itself depends on /usr/lib.

$ sudo crle -l /lib:/usr/lib:/usr/local/lib

ld.so.1: sudo: fatal: libdl.so.1: open failed: No such file or directory

Killed

In fact, remote access to the box will also fail because telnet, ftp and ssh will try to

access shared libraries which are no longer in the path.

$ telnet boson

Trying 10.11.11.51...

Connected to boson.particles.org.

Escape character is '^]'.

ld.so.1: in.telnetd: fatal: libdl.so.1: open failed: No such file ordirectory

Connection closed by foreign host.

And, while you can restore the functionality of many commands by setting your

LD_LIBRARY_PATH, this won't restore remote access -- and it won't restore your

sudo privileges because sudo, for fairly obvious security reasons, doesn't pay attention

to this environment variable.

While you can appeal to a higher authority (the guy who can exercise superuser

privilege without using sudo), there's also a workaround that you can use to regain

your superuser access without having to wait for someone with the root password to

come to your rescue.

The crle command had existed in Solaris since Solaris 7, but it most familiar to

systems administrators who need to augment library paths when installing applications

that install libraries in non-system locations such as /usr/local/lib or /opt/lib. Since it

8/12/2019 Manejo de Librera Solaris 11

4/4

established system-wide library paths, it is recommended over LD_LIBRARY_PATH

settings.

Para que arranque de Nuevo apache

crle -l /usr/lib:/usr/local/lib:/opt/mysql/mysql/lib/ (se realiza esto para que cargue las librerias de

mysql y pueda arrancar apache)

crlel /usr/lib:/usr/local/lib esto se realiza para que al reiniciar el servidor cargue las libreras de

inicia y salir del modo de mantenimiento