Chapter 41 Troubleshooting File Access Problems

This is a list of troubleshooting topics in this chapter.

• "Solving Problems With Search Paths (Command not found)"

• "Solving File Access Problems"

• "Recognizing Problems With Network Access"

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.

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

Use the which command to determine whether you are running the wrong version of the command.

$ which maker 
/usr/doctools/frame5.1/bin/maker

The which command looks in the .cshrc file for path information. The which command may give misleading results if you execute it from the Bourne or Korn shell and you have a .cshrc file than contains aliases for the which command. To ensure accurate results, use the which command in a C shell, or, in the Korn shell, use the whence command.

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
   Bourne and Korn	$HOME/.profile	$ PATH=$HOME/bin:/sbin:/usr/local /bin ... $ export PATH	A colon separates path names.
   C	$HOME/.cshrc or  $HOME/.login	hostname% set path=(~bin /sbin /usr/local/bin ...)	A blank space separates path names.

4. Activate the new path as follows:

   Shell	File Where Path Is Located	Activate The Path With ...
   Bourne and Korn	.profile	$ . ./.profile
   C	.cshrc	hostname% source .cshrc
   	.login	hostname% source .login

5. Verify the path using the command shown below.

   $ which command

Example--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 which command.

venus% mytool
mytool: Command not found
venus% which mytool
no mytool in /sbin /usr/sbin /usr/bin /etc /home/ignatz/bin  .
venus% echo $PATH
/sbin /usr/sbin /usr/bin /etc /home/ignatz/bin
venus% vi ~.cshrc
(Add appropriate command directory to the search path)
venus% source .cshrc
venus% 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), lpsched(1M) tells you the path is /usr/lib/lp/lpsched.

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.

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.

See Table 41-1 for information about how to change the permissions or ownership of a file that you are having problems accessing.

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 System Administration Guide, Volume 3 for information about problems with network access and problems with accessing systems through AutoFS.