Every file created in Oracle ASM gets a system-generated file name, otherwise known as a fully qualified file name. This is similar to a complete path name in a local file system.

Oracle ASM generates file names according to the following scheme:

+diskGroupName/databaseName/fileType/fileTypeTag.fileNumber.incarnation

An example of a fully qualified file name is the following:

+data/orcl/CONTROLFILE/Current.256.541956473

In the previous fully qualified file name, data is the disk group name, orcl is the database name, CONTROLFILE is the file type, and so on.

Only the slash (/) is supported by ASMCMD. File Names are not case sensitive, but are case retentive. If you type a path name as lowercase, ASMCMD retains the lowercase.

For more information about Oracle ASM file names, refer to Fully Qualified File Name Form.

As in other file systems, an Oracle ASM directory is a container for files, and an Oracle ASM directory can be part of a tree structure of other directories. The fully qualified file name represents a hierarchy of directories in which the plus sign (+) represents the root directory. In each disk group, Oracle ASM automatically creates a directory hierarchy that corresponds to the structure of the fully qualified file names in the disk group. The directories in this hierarchy are known as system-generated directories.

ASMCMD enables you to move up and down in this directory hierarchy with the cd (change directory) command. The ASMCMD ls (list directory) command lists the contents of the current directory, while the pwd command prints the name of the current directory.

When you start ASMCMD, the current directory is set to root (+). For an Oracle ASM instance with two disk groups, for example, data and fra, entering an ls command with the root directory as the current directory produces the following output:

ASMCMD> ls
data/
fra/

The following example demonstrates navigating the Oracle ASM directory tree (refer to the fully qualified file name shown previously):

ASMCMD> cd +data/orcl/CONTROLFILE
ASMCMD> ls
Current.256.541956473
Current.257.541956475

You can create your own directories as subdirectories of the system-generated directories using the ASMCMD mkdir command. The directories that you create can have subdirectories, and you can navigate the hierarchy of both system-generated directories and user-created directories with the cd command.

The following example creates the directory mydir under orcl in the disk group data:

ASMCMD> mkdir +data/orcl/mydir

If you start ASMCMD with the -p flag, then ASMCMD shows the current directory as part of its prompt. See Including the Current Directory in the ASMCMD Prompt.

ASMCMD [+] > cd data/orcl
ASMCMD [+data/orcl] >

ASMCMD retains the case of the directory that you entered.

Aliases are file names that are references or pointers to system-generated file names. However, aliases are user-friendly names. Aliases are similar to symbolic links in UNIX or Linux computers. You can create aliases to simplify Oracle ASM file name administration. You can create aliases with the mkalias ASMCMD command or a SQL ALTER DISKGROUP command.

An alias has at a minimum the disk group name as part of its complete path. You can create aliases at the disk group level or in any system-generated or user-created subdirectory. The following are examples of aliases:

+data/ctl1.f
+data/orcl/ctl1.f
+data/mydir/ctl1.f

If you run the ASMCMD ls (list directory) with the -l flag, each alias is listed with the system-generated file to which the alias refers.

ctl1.f => +data/orcl/CONTROLFILE/Current.256.541956473

For more information about aliases, refer to Alias Oracle ASM File Name Forms.

When you run an ASMCMD command that accepts a file name or directory name as an argument, you can use the name as either an absolute path or a relative path.

An absolute path refers to the full path of a file or directory. An absolute path begins with a plus sign (+) followed by a disk group name, followed by subsequent directories in the directory tree. The absolute path includes directories until the file or directory of interest is reached. A complete system-generated file name, otherwise known as the fully qualified file name, is an example of an absolute path to a file.

Using an absolute path enables the command to access the file or directory regardless of where the current directory is set. The following rm command uses an absolute path for the file name:

ASMCMD [+] > rm +data/orcl/datafile/users.259.555341963

The following cd command uses an absolute path to the directory.

ASMCMD [+data/mydir] > cd +data/orcl/CONTROLFILE

A relative path includes only the part of the file name or directory name that is not part of the current directory. That is, the path to the file or directory is relative to the current directory.

In the following example, the rm command operates on the file undotbs1.272.557429239, which in this case is a relative path. ASMCMD appends the current directory to the command argument to obtain the absolute path to the file. In this example this is +data/orcl/DATAFILE/undotbs1.272.557429239.

ASMCMD [+] > cd +data
ASMCMD [+data] > cd orcl/DATAFILE
ASMCMD [+data/orcl/DATAFILE] > ls
EXAMPLE.269.555342243
SYSAUX.257.555341961
SYSTEM.256.555341961
UNDOTBS1.258.555341963
UNDOTBS1.272.557429239
USERS.259.555341963
ASMCMD [+data/orcl/DATAFILE] >
 rm undotbs1.272.557429239

Paths to directories can also be relative. You can go up or down the hierarchy of the current directory tree branch by providing a directory argument to the cd command whose path is relative to the current directory.

In addition, you can use the pseudo-directories "." and ".." rather than a directory name. The "." pseudo-directory is the current directory. The ".." pseudo-directory is the parent directory of the current directory.

The following example demonstrates how to use relative directory paths and pseudo-directories:

ASMCMD [+data/orcl] > cd DATAFILE
ASMCMD [+data/orcl/DATAFILE] >cd ..
ASMCMD [+data/orcl] >

The wildcard characters * and % match zero or more characters anywhere within an absolute or relative path, which saves typing of the full directory or file name. The two wildcard characters behave identically. There are various ASMCMD commands that accept wildcards, such as cd, du, find, ls, lsattr, lsdg, lsdsk, lsgrp, lsusr, and rm.

If a wildcard pattern matches only one directory when using wildcard characters with cd, then cd changes the directory to that destination. If the wildcard pattern matches multiple directories, then ASMCMD does not change the directory but instead returns an error.

If you are running ASMCMD commands in noninteractive mode, then with most operating systems you must enclose the wildcard characters in quotes. For more information, refer to Running ASMCMD in Noninteractive Mode.

Example 10-1 illustrates the use of wildcards.

ASMCMD [+] > cd +data/orcl/*FILE
ASMCMD-08005: +data/orcl/*FILE: ambiguous

ASMCMD [+] > cd +data/orcl/C*
ASMCMD [+data/orcl/CONTROLFILE] >

ASMCMD [+] > ls +fra/orcl/A%
2009_07_13/
2009_07_14/

ASMCMD [+] >  ls +fra/orcl/ARCHIVELOG/2009%

+fra/orcl/ARCHIVELOG/2009_07_13/:
thread_1_seq_3.260.692103543
thread_1_seq_4.261.692108897
thread_1_seq_5.262.692125993
thread_1_seq_6.263.692140729
thread_1_seq_7.264.692143333
 
+fra/orcl/ARCHIVELOG/2009_07_14/:
thread_1_seq_8.271.692158265
thread_1_seq_9.272.692174597

ASMCMD [+] > ls data/orcl/*

+data/orcl/CONTROLFILE/:
Current.260.692103157

+data/orcl/DATAFILE/:
EXAMPLE.265.692103187
SYSAUX.257.692103045
SYSTEM.256.692103045
UNDOTBS1.258.692103045
USERS.259.692103045

+data/orcl/ONLINELOG/:
group_1.261.692103161
group_2.262.692103165
group_3.263.692103169

+data/orcl/PARAMETERFILE/:
spfile.266.692103315

+data/orcl/TEMPFILE/:
TEMP.264.692103181
spfileorcl.ora

The syntax for starting ASMCMD in interactive mode is:

asmcmd [-V]
asmcmd [--nocp] [-v {errors|warnings|normal|info|debug}]
       [--privilege connection_type ] [-p]
       [--inst instance_name] [--discover]

Table 10-2 summarizes the ASMCMD options.

The ORACLE_HOME and ORACLE_SID environment variables determine the instance to which ASMCMD connects. ASMCMD establishes a bequeath connection in the same manner as SQLPLUS / AS SYSASM which requires the user to be a member of the OSASM group.

When Oracle Flex ASM is enabled, ASMCMD connects to any one of the Oracle ASM instances running in the cluster. The connection to the Oracle ASM instance does not depend on the ORACLE_HOME and ORACLE_SID environment variables. The ASMCMD alert log shows which instance ASMCMD is connected to. If you want to connect to a specific Oracle ASM instance, then use the --inst option.

ASMCMD can be started with multiple options. For example:

asmcmd -p -v info

For the majority of the examples in this chapter, ASMCMD was started with the -p option.

1. Enter the following at the operating system command prompt:

   asmcmd

   Oracle displays an ASMCMD command prompt as follows:

   ASMCMD>

2. Enter an ASMCMD command and press Enter. The command runs and displays its output, if any, and then ASMCMD prompts for the next command.
3. Continue entering ASMCMD commands until you have completed the tasks.
4. Enter the exit or quit command to exit ASMCMD.

You can specify the --privilege option to choose the type of connection, either SYSASM or SYSDBA. The default value is SYSASM and is used when administering an Oracle ASM instance. Connect as SYSDBA when connecting to the database instance.

For example:

$ asmcmd --privilege sysasm

You can specify the -v option with the asmcmd command to display additional information with some commands to help users diagnose problems as shown in the following example:

$ asmcmd -v debug

When there is a message that must be logged during asmcmd operations, the message is written to the alert.log file or the trace.trc file.

The alert.log file is created or updated when asmcmd is started with the -v errors, -v warnings, or -v normal display level. The trace.trc file is created or updated when asmcmd is started with the -v info or -v debug display level.

By default, the alert.log is file created in the $ORACLE_BASE/diag/asmcmd/user_username/hostname/alert/ directory. By default, the trace.trc file is created in the $ORACLE_BASE/diag/asmcmd/user_username/hostname/trace/ directory.

Under certain circumstances, $ORACLE_BASE and $ORACLE_HOME can be set to override the default locations of the alert.log and trace.trc files.

You can specify the -p option with the asmcmd command to include the current directory in the ASMCMD prompt as shown in the following example:

$ asmcmd -p
ASMCMD [+] > cd data
ASMCMD [+data] >

You can specify the -V option when starting asmcmd to display the asmcmd version number. After displaying the version number, asmcmd immediately exits.

For example:

$ asmcmd -V
  asmcmd version 19.0.0.0.0