make: Interrupts
5.6 Interrupting or Killing 'make'
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If 'make' gets a fatal signal while a shell is executing, it may delete
the target file that the recipe was supposed to update. This is done if
the target file's last-modification time has changed since 'make' first
checked it.
The purpose of deleting the target is to make sure that it is remade
from scratch when 'make' is next run. Why is this? Suppose you type
'Ctrl-c' while a compiler is running, and it has begun to write an
object file 'foo.o'. The 'Ctrl-c' kills the compiler, resulting in an
incomplete file whose last-modification time is newer than the source
file 'foo.c'. But 'make' also receives the 'Ctrl-c' signal and deletes
this incomplete file. If 'make' did not do this, the next invocation of
'make' would think that 'foo.o' did not require updating--resulting in a
strange error message from the linker when it tries to link an object
file half of which is missing.
You can prevent the deletion of a target file in this way by making
the special target '.PRECIOUS' depend on it. Before remaking a target,
'make' checks to see whether it appears on the prerequisites of
'.PRECIOUS', and thereby decides whether the target should be deleted if
a signal happens. Some reasons why you might do this are that the
target is updated in some atomic fashion, or exists only to record a
modification-time (its contents do not matter), or must exist at all
times to prevent other sorts of trouble.
Info Catalog
make: Errors
make: Recipes
make: Recursion