exrecover daemon - Retrieve vi and ex files

Format

exrecover [-s] [name_file ...]
exrecover [-v]

Description

The exrecover daemon recovers text files from working files created by vi and ex. (These working files are in one or more temporary directories.) It is normally invoked from a system startup file before these working files are purged.

Options

-s: Suppresses error messages.
-v: Displays the version number of exrecover.

Environment variables

exrecover uses the following environment variables:

TMP_VI

Contains a directory path name that can be specified by an administrator as a location for vi temporary files. This is useful if the current default directory for these files (usually /tmp) is implemented as a TFS. In this case, all vi temporary files that the exrecover daemon uses for recovery would be gone after a system crash.

IBM® recommends that this environment variable be set by a system administrator as opposed to a user setting it for their environment. If the latter occurs and the user sets the TMP_VI directory to something different than what exrecover recognizes as TMP_VI, the user will need to run the exrecover daemon manually to allow the temporary files to be converted to the recoverable files used by vi (located in /etc/recover/$LOGNAME).

The system administrator should not do the following:

Set TMP_VI to /etc/recover/$LOGNAME.
Set TMP_VI to any directory where a path name component is an environment variable with a user's value different than the initialization process's value (for example, $HOME). vi temporary files are converted into a form recoverable by vi when exrecover is run during IPL. Because exrecover is issued during IPL, it is owned by the initialization process and will therefore contain different values for certain environment variables, if those environment variables are set. Throughout the file system, there may exist some temporary files that can only be converted by exrecover. This conversion can be done manually by a system administrator (to recover files owned by all users) or by a single user (to recover only their own files).

TMPDIR

The default directory. When this environment variable is set, exrecover looks in this directory for the ex and vi working files.

TMP

If TMPDIR is not set, TMP specifies the directory to be searched when looking for the ex and vi working files.

If both TMPDIR and TMP are not set, exrecover uses the directory that the XL C/C++ runtime library function tempnam() would use.

Localization

exrecover uses the following localization environment variables:

LANG
LC_ALL
LC_MESSAGES
NLSPATH

Files

exrecover uses the following files:

/tmp/VIl*: Line table files.
/tmp/VIn*: Name files.
/tmp/VIt*: Paged text files.
/etc/recover: The directory containing subdirectories of user names whose files have been recovered. Only users with the appropriate privileges, such as the system administrator, can create the /etc/recover directory.
/etc/recover/$LOGNAME/VIn*: Contains the name of the file that was being edited.
/etc/recover/$LOGNAME/VIt*: Contains the recovered text of the file that corresponds to the VIn* file

Using a TFS for vi temporary files will make it impossible to recover vi files after a system crash. vi writes temporary files to TMP_VI or TMPDIR (or /tmp by default), and if the system crashes, those files can be recovered by the exrecover command, which automatically runs from /etc/rc. If the files are written to a TFS, then they will be wiped out when the system is IPLed. See the TMP_VI description under Environment Variables section of this command.

Usage notes

To recover all the files in the temporary directory, this command must be run with appropriate permissions (for example, superuser privileges) so the recovered files can be stored in the /etc/recover directory with the appropriate ownerships and permissions.
For example, the following is a shell script to recover the files from TMPDIR, where TMPDIR is the default directory:
```
export TMPDIR=/tmp
exrecover
 
```
If it is invoked by a nonprivileged user (for example, a user who is not a root user), then only those files that are owned by that user are recovered. Because vi and ex create their working files in directories that are specified by the TMPDIR or TMP environment variables, one of these environment variables must be set before exrecover can be issued.
For example, the following is a shell script that recovers files from $HOME/tmp:
```
export TMPDIR=$HOME/tmp
exrecover
 
```
exrecover is also invoked by vi or ex when you issue the ex preserve command or when exrecover receives a SIGHUP signal. The working files created by vi and ex are found in a default temporary directory (such as /tmp) or in the directory specified by the TMPDIR or in the directory specified by the TMP_VI, TMPDIR, or TMP environment variable. Three working files are created:

name_file

Contains the actual name of the vi file. The names of all name_files begin with VIn.

line_table_file

Contains a dummy page followed by data that gives, in line number order, the offset for each line of text in the corresponding paged_text_file. The page size is typically 1K, but may vary on some systems. The names of all line table files begin with VIl.

paged_text_file

Contains lines of text that are at most LINE_MAX bytes in length. Lines shorter than LINE_MAX byte are ended by a newline. The names of all paged text files begin with VIt.
You can also run the program by specifying name_file on the command line. For example:
```
exrecover /tmp/VInaaaa.111 /tmp/VInbbbb.222 ...
```
exrecover searches for a name_file and tries to open the associated line table and paged text files. If all these files are found, exrecover builds, from the line table and paged text files, a text file and stores it in the directory /etc/recover/$LOGNAME.
It also stores a corresponding name_file to identify the file that was recovered and sends mail, using the mailx utility, to the owner of the file indicating the date, time, and name of the file recovered. You can retrieve recovered files in one of the following ways:
```
vi -r file [issued from a shell command line]
ex -r file [issued from a shell command line]
:recover file [issued from within a vi session]
```
Each command loads the most recent occurrence of the file recovered from a system failure or the ex preserve command. If vi successfully loads the file, it removes the preserved file.

Exit values

0

Successful completion.

1

Failure due to any of the following reasons:

Memory allocation error.
No working files were found.
No /etc/recover directory errors that affect the overall operation of the exrecover command.
An incomplete set of working files were found.

2

Usage error.

3

An error occurred while recovering a specific file. Some, but not all, files were recovered.

Related information

ex, vi