Troubleshooting File Access Problems

Users frequently experience problems, and call on a system administrator for help, because they cannot access a program, a file, or a directory that they could previously use.

Whenever you encounter such a problem, investigate one of three areas:

• The user's search path may have been changed, or the directories in the search path may not be in the proper order.

• The file or directory may not have the proper permissions or ownership.

• The configuration of a system accessed over the network may have changed.

This chapter briefly describes how to recognize problems in each of these three areas and suggests possible solutions.

Solving Problems With Search Paths (Command not found)

A message of Command not found indicates one of the following:

• The command is not available on the system.

• The command directory is not in the search path.

To fix a search path problem, you need to know the pathname of the directory where the command is stored.

If the wrong version of the command is found, a directory that has a command of the same name is in the search path. In this case, the proper directory may be later in the search path or may not be present at all.

You can display your current search path by using the echo $PATH command. For example:

$ echo $PATH 
/home/kryten/bin:/sbin:/usr/sbin:/usr/bin:/usr/dt:/usr/dist/exe

Use the type command to determine whether you are running the wrong version of the command. For example:

$ type acroread 
acroread is /usr/bin/acroread

How to Diagnose and Correct Search Path Problems

1. Display the current search path to verify that the directory for the command is not in your path or that it isn't misspelled.

   $ echo $PATH 

2. Check the following:

   • Is the search path correct?

   • Is the search path listed before other search paths where another version of the command is found?

   • Is the command in one of the search paths?

   If the path needs correction, go to step 3. Otherwise, go to step 4.

3. Add the path to the appropriate file, as shown in this table.
   

   Shell File Syntax Notes bash and ksh93 $HOME/.profile $ PATH=$HOME/bin:/sbin:/usr/local /bin ... $ export PATH A colon separates path names.

4. Activate the new path as follows:
   

   Shell Path Location Command to Activate The Path bash and ksh93 .profile $ . ./.profile .login hostname% source .login

5. Verify the new path.

   $ which command

Example 6-6 Diagnosing and Correcting Search Path Problems

This example shows that the mytool executable is not in any of the directories in the search path using the type command.

 $ mytool
  -bash: mytool: command not found
  $ type mytool
  -bash: type: mytool: not found
  $ echo $PATH
  /usr/bin:
  $ vi $HOME/.profile
  (Add appropriate command directory to the search path)
  $ . $HOME/.profile
  $ mytool

If you cannot find a command, look at the man page for its directory path. For example, if you cannot find the lpsched command (the lp printer daemon), the lpsched(1M) man page tells you the path is /usr/lib/lp/lpsched.

Changing File and Group Ownerships

Frequently, file and directory ownerships change because someone edited the files as superuser. When you create home directories for new users, be sure to make the user the owner of the dot (.) file in the home directory. When users do not own “.” they cannot create files in their own home directory.

Access problems can also arise when the group ownership changes or when a group of which a user is a member is deleted from the /etc/group database.

For information about how to change the permissions or ownership of a file that you are having problems accessing, see Chapter 7, Controlling Access to Files (Tasks), in System Administration Guide: Security Services.

Solving File Access Problems

When users cannot access files or directories that they previously could access, the permissions or ownership of the files or directories probably has changed.

Recognizing Problems With Network Access

If users have problems using the rcp remote copy command to copy files over the network, the directories and files on the remote system may have restricted access by setting permissions. Another possible source of trouble is that the remote system and the local system are not configured to allow access.

See Strategies for NFS Troubleshooting in System Administration Guide: Network Services for information about problems with network access and problems with accessing systems through AutoFS.