Appendix A. Online Help
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## Appendix A. Online Help

This appendix contains help screens accessible from the `cview` window's Help menu.

## Overview

IRIX Checkpoint and Restart (CPR) is a facility for saving a running process or set of processes and, at some later time, restarting the saved process(es) from the point already reached. A checkpoint image is saved in a directory, and restarted by reading saved state from this directory to resume execution.

The `cview` window provides a graphical user interface for checkpointing, restarting checkpoints, querying checkpoint status, and deleting statefiles. Two tabs at the bottom of the `cview` window select either the checkpoint or restart control panel.

## How to Checkpoint

Under the STEP I button, select a process or set of processes from the list. To checkpoint a process group, a session group, an IRIX array session, a process hierarchy, an IRIX job, or an sproc shared group, select a category from the Individual Process drop-down menu. In the filename field below, enter the name of a directory for storing the statefile.

Click the STEP II button if you want to change checkpoint options, such as whether to exit or continue the process, or control open file and mapped file dispositions.

Click the STEP III OK button to initiate the checkpoint, or the Cancel Checkpoint button to discontinue.

## How to Restart

Click the Restart Control Panel tab at the bottom of the `cview` window.

From the scrolling list of files and directories, select a statefile to restart. Note that all files and directories are shown, not just statefile directories. If a statefile is located somewhere besides your home directory, change directories using the icon finder at the top.

Select any options you want, such as whether to retain the original process ID, whether to restore the original working directory, or whether to restore the original root directory.

Click the OK Go Restart button to initiate restart.

## Querying a Statefile

Click the Restart Control Panel tab at the bottom of the `cview` window.

From the scrolling list of files and directories, select a statefile to query. Note that all files and directories are shown, not just statefile directories. If a statefile is located somewhere besides your home directory, change directories using the icon finder at the top.

At the bottom of the `cview` window, click the Tell Me More About This Statefile button.

## Deleting a Statefile

Click the Restart Control Panel tab at the bottom of the `cview` window.

From the scrolling list of files and directories, select a statefile to delete. Note that all files and directories are shown, not just statefile directories. If a statefile is located somewhere besides your home directory, change directories using the icon finder at the top.

At the bottom of the `cview` window, click the Remove This Statefile button.

## Checkpoint Widgets

### Step I Button

Click this button to poll the system for processes owned by the user listed on the right.

### User Drop Pocket

This is the drop pocket for the process owner.

### User Name

This is the text entry field for the process owner. To look at processes for a different user, type a valid user name into this text entry field, and press Enter or click the STEP I button.

### User Recycle

This is the recycle button for the process owner. Each time you change the process owner, the recycle list grows, providing a shortcut next time you want to switch process owners.

### Process List

This is a list of processes on the system owned by the specified user. Column headings indicate the following values:

USER |  | user name
PID |  | process ID
PPID |  | parent process ID
PGID |  | process group ID
SID |  | session group ID
JID |  | IRIX job ID
ASH |  | IRIX Array Session ID
COMMAND |  | the command string with arguments

### Process Types

This drop-down menu controls whether to checkpoint an individual process, a process group, a process session, an IRIX array session, a process hierarchy, or a `sproc` shared group. Be sure to select a set of processes from the list above that can be checkpointed as the process type you select. Process types are as follows:

- UNIX process ID; see `ps(1)`

- UNIX process group ID; see `setpgrp(2)`

- UNIX process session ID; see `setsid(2)`

- IRIX array session ID; see `array_sessions(5)`

- Process hierarchy (tree) rooted at the given process ID

- IRIX `sproc()` shared group; see `sproc(2)`

- IRIX job ID; see `job_limits(5)`

### Statefile Field

A statefile is a directory containing information about a process or set of processes, including the names of open files and system objects. Statefiles contain all available information about a running process, to enable restart. Statefiles are stored as files inside a directory, protected by normal IRIX security mechanisms.

### Statefile Drop Pocket

This is the drop pocket for the statefile name. You may drag a directory icon from another desktop application and drop it here.

### Statefile Name

This is the text entry field for the statefile name. Enter a pathname here, and a statefile directory will be created in the location you specify.

### System Upgrade

Click here if you intend to upgrade operating system software before restarting this set of processes. When you checkpoint for system upgrade, CPR saves not only open file and process states, but also any system commands and libraries that are necessary to restart the statefile accurately.

### Step II Button

This section of the checkpoint control panel sets checkpoint attributes, similar to the attributes controlled by the `cpr` command's `$HOME/.cpr` file. Click this button to display open files and mapped files in the scrolling list below.

### Exit or Continue

This drop-down menu controls whether the selected process(es) exit after checkpointing, or whether they continue running. The default is to exit.

### File Dispositions

This drop-down menu controls how CPR treats files that the selected process has open at checkpoint time. The five choices are as follows:

MERGE |  | No explicit file save at checkpoint. Upon restart, reopen the file and seek to the previous offset. This may be used for files that are not modified after checkpoint, or for files where it is acceptable to overwrite changes made between checkpoint and restart time, particularly past the saved offset point. If programs seek before writing, changes preceding the offset point could be overwritten as well.
IGNORE |  | No explicit file save at checkpoint. Upon restart, reopen the file as it was originally opened, at offset zero (even if originally opened for append). If the file was originally opened for writing, as with the `fopen()` “w” or “a” flag, this action has the effect of overwriting the entire file.
APPEND |  | No explicit file save at checkpoint. Upon restart, append to the end of the file. This disposition is good for log files.
REPLACE |  | Explicitly save the file at checkpoint. Upon restart, replace the original file with the saved one. Any changes made to the original file between checkpoint and restart time are overwritten by the saved file.
SUBSTITUTE |  | Explicitly save the file at checkpoint. Upon restart, reopen the saved file as an anonymous substitution for the original file. This is similar to the REPLACE mode except that the original file remains untouched, unless specifically altered by the program.

### Open File List

After you click the Step II button, this list shows all open files for the selected process(es), and the open file dispositions in effect for each file.

### OK Button

Click this button to initiate a checkpoint with the options you have selected above.

### Cancel Button

Click this button to cancel the checkpoint options you have selected.

### Tab Controls

The `cview` window contains two control panels in one: the Checkpoint Control Panel and Restart Control Panel. Click one of these tabs to select the control panel you want.

## Restart Widgets

### List Button

Click this button to list files and directories in the pathname displayed just below.

### Finder Drop Pocket

This is the drop pocket for the pathname. You may drag a directory icon from another desktop application and drop it here.

### Finder Pathname

This is the text field for the current pathname. To look at files in a different directory, modify the displayed pathname as you wish, and press Enter or click the button above.

### Finder Recycle

This is the recycle button for the pathname. Each time you change the pathname, the recycle list grows, providing a shortcut next time you want to switch pathnames.

### Statefile List

This is a list of all files in the directory specified in the finder pathname above. File details such as owner and modification time are shown on the right. Select a statefile from this list, or change directories by changing the finder pathname.

### Process ID Menu

This drop-down menu controls how processes are forked at restart time. The default is to restart using the original process IDs. If this proves impossible, select the Any Process ID option instead.

### Original Working Directory

If you don't care about the working directory for restarted processes, click the checkbox saying “Don't restore the original working directory.”

### Original Root Directory

If you don't care about the root directory for restarted processes, click the checkbox saying “Don't restore the original root directory.”

### Restart Button

Click this button to initiate restart from the selected statefile.

### Tell Me More Button

Click this button to query the selected statefile for status information.

### Remove Statefile Button

Click this button to delete the selected statefile from the filesystem.

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