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1.12 Helpful Information

This section contains assorted helpful information which may be useful in staying out of trouble or getting out of trouble.

• It is possible to get some sort of help nearly everywhere by typing Home or C-_.
• Various commands take over the keyboard and insist that you type the key-events that they want as input. If you get in such a situation and want to get out, you can usually do so by typing C-g some small number of times. If this fails you can try typing C-x C-z to exit Hemlock and then "(ed)" to re-enter it.
• Before you quit, make sure you have saved all your changes. C-u C-x C-b will display a list of all modified buffers. If you exit using C-x M-z, then Hemlock will save all modified buffers with associated files.
• If you lose changes to a file due to a crash or accidental failure to save, look for backup ("file.BAK") or checkpoint ("file.CKP") files in the same directory where the file was.
• If the screen changes unexpectedly, you may have accidentally typed an incorrect command. Use Home l to see what it was. If you are not familiar with the command, use Home c to see what it is so that you know what damage has been done. Many interesting commands can be found in this fashion. This is an example of the much-underrated learning technique known as "Learning by serendipitous malcoordination". Who would ever think of looking for a command that deletes all files in the current directory?
• If you accidentally type a "killing" command such as C-w, you can get the lost text back using C-y. The Undo command is also useful for recovering from this sort of problem.

Hemlock Variable: Region Query Size (initial value 30) ¶

Various commands ask for confirmation before modifying a region containing more than this number of lines. If this is nil, then these commands refrain from asking, no matter how large the region is.

Command: Undo ¶

This command undoes the last major modification. Killing commands and some other commands save information about their modifications, so accidental uses may be retracted. This command displays the name of the operation to be undone and asks for confirmation. If the affected text has been modified between the invocations of Undo and the command to be undone, then the result may be somewhat incorrect but useful. Often Undo itself can be undone by invoking it again.