These signals are used to report various errors generated by an operation done by the program. They do not necessarily indicate a programming error in the program, but an error that prevents an operating system call from completing. The default action for all of them is to cause the process to terminate.
Broken pipe. If you use pipes or FIFOs, you have to design your
application so that one process opens the pipe for reading before
another starts writing. If the reading process never starts, or
terminates unexpectedly, writing to the pipe or FIFO raises a
SIGPIPE signal. If
SIGPIPE is blocked, handled or
ignored, the offending call fails with
Pipes and FIFO special files are discussed in more detail in Pipes and FIFOs.
Another cause of
SIGPIPE is when you try to output to a socket
that isn’t connected. See Sending Data.
Resource lost. This signal is generated when you have an advisory lock on an NFS file, and the NFS server reboots and forgets about your lock.
On GNU/Hurd systems,
SIGLOST is generated when any server program
dies unexpectedly. It is usually fine to ignore the signal; whatever
call was made to the server that died just returns an error.
CPU time limit exceeded. This signal is generated when the process exceeds its soft resource limit on CPU time. See Limiting Resource Usage.