5 ms·

Shouldn't that explanation be by followed by 'in order to request the termination of the process'?

by ababab 13y ago

beedogs 13y ago
Not necessarily. You can send the CONTinue signal to a process using the kill command. This will not cause the process to terminate.
- twinge 13y ago
  Or use "kill -0 <pid>" to check if a signal can be sent/the pid exists.
  - rahimnathwani 13y ago
    Or use kill -USR1 <pid> to check the progress of dd
    - DHowett 13y ago
      Only if you've enabled it. If you've not, the process will terminate unceremoniously (in a mechanism borne entirely out of hatred for users.) This is my favourite part of dd: The "will I receive a status report or will I terminate my long-running copy?" gamble.
      - jsight 13y ago
        Is that a BSD thing? I've never had to enable it on Linux to avoid killing the process.
        rahimnathwani 13y ago
        Me neither, on debian.
    - Freaky 13y ago
      It's SIGINFO on the BSD's, and works with just about any process (though obviously not everything has a customized handler). Also handily mapped to Ctrl-T.
habosa 13y ago
Not always. The kill system call can be used to send any signal, it's just got a name that implies you're sending something like SIGKILL or SIGTERM. I have written C programs that use kill for harmless inter-process communication.
- eru 13y ago
  SIGUSER is quite common for that. Or SIGHUP.
  - brokenparser 13y ago
    By convention, SIGHUP is used by daemons to signal a change of configuration.
nailer 13y ago
You can also cancel (sigint, eg ctrl c) processes via kill. Or use sigchld to a parent to get rid of zombie children.
brokenparser 13y ago
No because only SIGQUIT, SIGABRT, SIGKILL, SIGTERM and often SIGHUP are supposed to do that. All of the other signals have wildly varying meanings. See man 7 signal: http://unixhelp.ed.ac.uk/CGI/man-cgi?signal+7 http://unixhelp.ed.ac.uk/CGI/man-cgi?signal+7
drivers99 13y ago
SIGHUP is also used to tell some certain daemons to re-read their configuration files without quitting.

Shouldn't that explanation be by followed by 'in order to request the termination of the process'?

by ababab 13y ago

Shouldn't that explanation be by followed by 'in order to request the termination of the process'?

Not necessarily. You can send the CONTinue signal to a process using the kill command. This will not cause the process to terminate.

twinge 13y ago
Or use "kill -0 <pid>" to check if a signal can be sent/the pid exists.
- rahimnathwani 13y ago
  Or use kill -USR1 <pid> to check the progress of dd
  - DHowett 13y ago
    Only if you've enabled it. If you've not, the process will terminate unceremoniously (in a mechanism borne entirely out of hatred for users.) This is my favourite part of dd: The "will I receive a status report or will I terminate my long-running copy?" gamble.
    - jsight 13y ago
      Is that a BSD thing? I've never had to enable it on Linux to avoid killing the process.
      - rahimnathwani 13y ago
        Me neither, on debian.
  - Freaky 13y ago
    It's SIGINFO on the BSD's, and works with just about any process (though obviously not everything has a customized handler). Also handily mapped to Ctrl-T.

habosa 13y ago

Not always. The kill system call can be used to send any signal, it's just got a name that implies you're sending something like SIGKILL or SIGTERM. I have written C programs that use kill for harmless inter-process communication.

eru 13y ago
SIGUSER is quite common for that. Or SIGHUP.
- brokenparser 13y ago
  By convention, SIGHUP is used by daemons to signal a change of configuration.

nailer 13y ago

You can also cancel (sigint, eg ctrl c) processes via kill. Or use sigchld to a parent to get rid of zombie children.

brokenparser 13y ago

No because only SIGQUIT, SIGABRT, SIGKILL, SIGTERM and often SIGHUP are supposed to do that. All of the other signals have wildly varying meanings. See man 7 signal: http://unixhelp.ed.ac.uk/CGI/man-cgi?signal+7 http://unixhelp.ed.ac.uk/CGI/man-cgi?signal+7

drivers99 13y ago

SIGHUP is also used to tell some certain daemons to re-read their configuration files without quitting.