DragonFly On-Line Manual Pages
CHECKPT(1) DragonFly General Commands Manual CHECKPT(1)
checkpt -- resume checkpointed program
checkpt -r file.ckpt
The checkpt utility will resume the checkpointed program from the speci-
fied checkpoint file. Programs can be checkpointed using ^E.
By default, only members of the wheel group can checkpoint a program.
The group can be changed with the sysctl kern.ckptgroup. The checkpoint
file template can be changed with the sysctl kern.ckptfile.
The checkpointing utility is fairly primitive. Only programs operating
on normal files can be properly restored. Programs which operate on
devices, sockets, or pipes (including piped commands) cannot be com-
pletely. File descriptors 0, 1, and 2, are not saved and the restored
program will inherit the descriptors from checkpt.
Programs can actively support checkpointing by catching the SIGCKPT sig-
nal, cleaning up, and manually calling the sys_checkpoint() system call.
The program can then choose whether to continue running or exit. The
resumed program will get a (typically) positive return value from
sys_checkpoint() which it can use to determine whether it just made the
system call or whether it is being resumed from the system call. The
program can then reconstruct non-checkpointed elements and resume.
The checkpt command first appeared in DragonFly 1.0.
DragonFly 4.1 October 19, 2003 DragonFly 4.1