How to prevent a background process from being stopped after closing SSH client in Linux

Question

I m working on a Linux machine through SSH  Putty   I need to leave a process running during the night  so I thought I could do that by starting the process in background  with an ampersand at the end of the command  and redirecting stdout to a file   To my surprise  that doesn t work  As soon as I close the Putty window  the process is stopped   How can I prevent that from happening

User · Answer

When the session is closed the process receives the SIGHUP signal which it is apparently not catching   You can use the nohup command when launching the process or the bash built-in command disown -h after starting the process to prevent this from happening    gt  help disown disown  disown  -h   -ar   jobspec           By default  removes each JOBSPEC argument from the table of active jobs      If the -h option is given  the job is not removed from the table  but is     marked so that SIGHUP is not sent to the job if the shell receives a     SIGHUP   The -a option  when JOBSPEC is not supplied  means to remove all     jobs from the job table  the -r option means to remove only running jobs

User · Answer

As others have noted  to run a process in the background so that you can disconnect from your SSH session  you need to have the background process properly disassociate itself from its controlling terminal - which is the pseudo-tty that the SSH session uses   You can find information about daemonizing processes in books such as Stevens   Advanced Network Program  Vol 1  3rd Edn  or Rochkind s  Advanced Unix Programming    I recently  in the last couple of years  had to deal with a recalcitrant program that did not daemonize itself properly   I ended up dealing with that by creating a generic daemonizing program - similar to nohup but with more controls available   Usage  daemonize  -abchptxV  -d dir  -e err  -i in  -o out  -s sigs  -k fds  -m umask  -- command  args       -V          print version and exit   -a          output files in append mode  O APPEND    -b          both output and error go to output file   -c          create output files  O CREAT    -d dir      change to given directory   -e file     error file  standard error -  dev null    -h          print help and exit   -i file     input file  standard input -  dev null    -k fd-list  keep file descriptors listed open   -m umask    set umask  octal    -o file     output file  standard output -  dev null    -s sig-list ignore signal numbers   -t          truncate output files  O TRUNC    -p          print daemon PID on original stdout   -x          output files must be new  O EXCL    The double-dash is optional on systems not using the GNU getopt   function  it is necessary  or you have to specify POSIXLY CORRECT in the environment  on Linux etc   Since double-dash works everywhere  it is best to use it   You can still contact me  firstname dot lastname at gmail dot com  if you want the source for daemonize   However  the code is now  finally  available on GitHub in my SOQ  Stack Overflow Questions  repository as file daemonize-1 10 tgz in the packages sub-directory

User · Answer

Personally  I like the  batch  command     batch  gt  mycommand -x arg1 -y arg2 -z arg3  gt   D   This stuffs it in to the background  and then mails the results to you  It s a part of cron

User · Answer

Accepted answer suggest using nohup  I would rather suggest using pm2  Using pm2 over nohup has many advantages  like keeping the application alive  maintain log files for application and lot more other features  For more detail check this out    To install pm2 you need to download npm  For Debian based system  sudo apt-get install npm   and for Redhat    sudo yum install npm   Or you can follow these instruction  After installing npm use it to install pm2    npm install pm2 latest -g   Once its done you can start your application by      pm2 start app js                Start  Daemonize and auto-restart application  Node    pm2 start app py                Start  Daemonize and auto-restart application  Python    For process monitoring use following commands       pm2 list                        List all processes started with PM2   pm2 monit                       Display memory and cpu usage of each app   pm2 show  app-name              Show all informations about application   Manage processes using either app name or process id or manage all processes together       pm2 stop      lt app name id  all  json conf gt    pm2 restart   lt app name id  all  json conf gt    pm2 delete    lt app name id  all  json conf gt    Log files can be found in     HOME  pm2 logs  contain all applications logs     Binary executable files can also be run using pm2  You have to made a change into the jason file  Change the  exec interpreter     node   to  exec interpreter     none    see the attributes section      include  lt stdio h gt   include  lt unistd h gt     No standard C library int main void        printf  Hello World n        sleep  100       printf  Hello World n         return 0      Compiling above code    gcc -o hello hello c     and run it with np2 in the background    pm2 start   hello

User · Answer

For most processes you can pseudo-daemonize using this old Linux command-line trick       mycommand  amp   amp     For example       sleep 30  amp   amp     exit   Then start a new terminal window and     ps aux   grep sleep   Will show that sleep 30 is still running   What you have done is started the process as a child of a child  and when you exit  the nohup command that would normally trigger the process to exit doesn t cascade down to the grand-child  leaving it as an orphan process  still running   I prefer this  set it and forget it  approach  no need to deal with nohup  screen  tmux  I o redirection  or any of that stuff

User · Answer

There s also the daemon command of the open-source libslack package   daemon is quite configurable and does care about all the tedious daemon stuff such as automatic restart  logging or pidfile handling

User · Answer

On a Debian-based system  on the remote machine  Install   sudo apt-get install tmux  Usage   tmux run commands you want  To rename session   Ctrl B then   set Name  To exit session   Ctrl B then D   this leaves the tmux session   Then  you can log out of SSH  When you need to come back check on it again  start up SSH  and enter  tmux attach session name  It will take you back to your tmux session

User · Answer

Nohup allows a client process to not be killed if a the parent process is killed  for argument when you logout   Even better still use   nohup  bin sh -c  echo       gt   pidfile  exec  FOO BIN  FOO CONFIG     gt   dev null   Nohup makes the process you start immune to termination which your SSH session and its child processes are kill upon you logging out   The command i gave provides you with a  way you can store the pid of the application in a pid file so that you can correcly kill it later and allows the process to run after you have logged out

User · Answer

I would recommend using GNU Screen   It allows you to disconnect from the server while all of your processes continue to run   I don t know how I lived without it before I knew it existed

User · Answer

Personally  I like the  batch  command     batch  gt  mycommand -x arg1 -y arg2 -z arg3  gt   D   This stuffs it in to the background  and then mails the results to you  It s a part of cron

User · Answer

nohup is very good if you want to log your details to a file  But when it goes to background you are unable to give it a password if your scripts ask for  I think you must try screen  its a utility you can install on your linux distribution using yum for example on CentOS yum install screen then access your server via putty or another software  in your shell type screen  It will open screen 0  in putty  Do your work  You can create more screen 1   screen 2   etc in same putty session  Basic commands you need to know  To start screen screen  To create next screen ctrl a c  To move to next screen you created ctrl a n  To detach ctrl a d  During work close your putty  And next time when you login via putty type screen -r To reconnect to your screen  and you can see your process still running on screen  And to exit the screen type  exit  For more details see man screen

User · Answer

Personally  I like the  batch  command     batch  gt  mycommand -x arg1 -y arg2 -z arg3  gt   D   This stuffs it in to the background  and then mails the results to you  It s a part of cron

User · Answer

On systemd Linux  systemd-run is a nice tool to launch session-independent processes

User · Answer

As others have noted  to run a process in the background so that you can disconnect from your SSH session  you need to have the background process properly disassociate itself from its controlling terminal - which is the pseudo-tty that the SSH session uses   You can find information about daemonizing processes in books such as Stevens   Advanced Network Program  Vol 1  3rd Edn  or Rochkind s  Advanced Unix Programming    I recently  in the last couple of years  had to deal with a recalcitrant program that did not daemonize itself properly   I ended up dealing with that by creating a generic daemonizing program - similar to nohup but with more controls available   Usage  daemonize  -abchptxV  -d dir  -e err  -i in  -o out  -s sigs  -k fds  -m umask  -- command  args       -V          print version and exit   -a          output files in append mode  O APPEND    -b          both output and error go to output file   -c          create output files  O CREAT    -d dir      change to given directory   -e file     error file  standard error -  dev null    -h          print help and exit   -i file     input file  standard input -  dev null    -k fd-list  keep file descriptors listed open   -m umask    set umask  octal    -o file     output file  standard output -  dev null    -s sig-list ignore signal numbers   -t          truncate output files  O TRUNC    -p          print daemon PID on original stdout   -x          output files must be new  O EXCL    The double-dash is optional on systems not using the GNU getopt   function  it is necessary  or you have to specify POSIXLY CORRECT in the environment  on Linux etc   Since double-dash works everywhere  it is best to use it   You can still contact me  firstname dot lastname at gmail dot com  if you want the source for daemonize   However  the code is now  finally  available on GitHub in my SOQ  Stack Overflow Questions  repository as file daemonize-1 10 tgz in the packages sub-directory

User · Answer

nohup is very good if you want to log your details to a file  But when it goes to background you are unable to give it a password if your scripts ask for  I think you must try screen  its a utility you can install on your linux distribution using yum for example on CentOS yum install screen then access your server via putty or another software  in your shell type screen  It will open screen 0  in putty  Do your work  You can create more screen 1   screen 2   etc in same putty session  Basic commands you need to know  To start screen screen  To create next screen ctrl a c  To move to next screen you created ctrl a n  To detach ctrl a d  During work close your putty  And next time when you login via putty type screen -r To reconnect to your screen  and you can see your process still running on screen  And to exit the screen type  exit  For more details see man screen

User · Answer

As others have noted  to run a process in the background so that you can disconnect from your SSH session  you need to have the background process properly disassociate itself from its controlling terminal - which is the pseudo-tty that the SSH session uses   You can find information about daemonizing processes in books such as Stevens   Advanced Network Program  Vol 1  3rd Edn  or Rochkind s  Advanced Unix Programming    I recently  in the last couple of years  had to deal with a recalcitrant program that did not daemonize itself properly   I ended up dealing with that by creating a generic daemonizing program - similar to nohup but with more controls available   Usage  daemonize  -abchptxV  -d dir  -e err  -i in  -o out  -s sigs  -k fds  -m umask  -- command  args       -V          print version and exit   -a          output files in append mode  O APPEND    -b          both output and error go to output file   -c          create output files  O CREAT    -d dir      change to given directory   -e file     error file  standard error -  dev null    -h          print help and exit   -i file     input file  standard input -  dev null    -k fd-list  keep file descriptors listed open   -m umask    set umask  octal    -o file     output file  standard output -  dev null    -s sig-list ignore signal numbers   -t          truncate output files  O TRUNC    -p          print daemon PID on original stdout   -x          output files must be new  O EXCL    The double-dash is optional on systems not using the GNU getopt   function  it is necessary  or you have to specify POSIXLY CORRECT in the environment  on Linux etc   Since double-dash works everywhere  it is best to use it   You can still contact me  firstname dot lastname at gmail dot com  if you want the source for daemonize   However  the code is now  finally  available on GitHub in my SOQ  Stack Overflow Questions  repository as file daemonize-1 10 tgz in the packages sub-directory

User · Answer

If you re willing to run X applications as well - use xpra together with  screen

User · Answer

Use screen  It is very simple to use and works like vnc for terminals  http   www bangmoney org presentations screen html

User · Answer

nohup blah  amp    Substitute your process name for blah

User · Answer

There s also the daemon command of the open-source libslack package   daemon is quite configurable and does care about all the tedious daemon stuff such as automatic restart  logging or pidfile handling

User · Answer

If you use screen to run a process as root  beware of the possibility of privilege elevation attacks  If your own account gets compromised somehow  there will be a direct way to take over the entire server   If this process needs to be run regularly and you have sufficient access on the server  a better option would be to use cron the run the job  You could also use init d  the super daemon  to start your process in the background  and it can terminate as soon as it s done

User · Answer

When the session is closed the process receives the SIGHUP signal which it is apparently not catching   You can use the nohup command when launching the process or the bash built-in command disown -h after starting the process to prevent this from happening    gt  help disown disown  disown  -h   -ar   jobspec           By default  removes each JOBSPEC argument from the table of active jobs      If the -h option is given  the job is not removed from the table  but is     marked so that SIGHUP is not sent to the job if the shell receives a     SIGHUP   The -a option  when JOBSPEC is not supplied  means to remove all     jobs from the job table  the -r option means to remove only running jobs

User · Answer

If you use screen to run a process as root  beware of the possibility of privilege elevation attacks  If your own account gets compromised somehow  there will be a direct way to take over the entire server   If this process needs to be run regularly and you have sufficient access on the server  a better option would be to use cron the run the job  You could also use init d  the super daemon  to start your process in the background  and it can terminate as soon as it s done

User · Answer

nohup blah  amp    Substitute your process name for blah

User · Answer

Use screen  It is very simple to use and works like vnc for terminals  http   www bangmoney org presentations screen html

User · Answer

Check out the  nohup  program

User · Answer

I used screen command  This link has detail as to how to do this  https   www rackaid com blog linux-screen-tutorial-and-how-to  starting

User · Answer

For most processes you can pseudo-daemonize using this old Linux command-line trick       mycommand  amp   amp     For example       sleep 30  amp   amp     exit   Then start a new terminal window and     ps aux   grep sleep   Will show that sleep 30 is still running   What you have done is started the process as a child of a child  and when you exit  the nohup command that would normally trigger the process to exit doesn t cascade down to the grand-child  leaving it as an orphan process  still running   I prefer this  set it and forget it  approach  no need to deal with nohup  screen  tmux  I o redirection  or any of that stuff

User · Answer

Personally  I like the  batch  command     batch  gt  mycommand -x arg1 -y arg2 -z arg3  gt   D   This stuffs it in to the background  and then mails the results to you  It s a part of cron

User · Answer

Nohup allows a client process to not be killed if a the parent process is killed  for argument when you logout   Even better still use   nohup  bin sh -c  echo       gt   pidfile  exec  FOO BIN  FOO CONFIG     gt   dev null   Nohup makes the process you start immune to termination which your SSH session and its child processes are kill upon you logging out   The command i gave provides you with a  way you can store the pid of the application in a pid file so that you can correcly kill it later and allows the process to run after you have logged out

User · Answer

Use screen  It is very simple to use and works like vnc for terminals  http   www bangmoney org presentations screen html

User · Answer

Check out the  nohup  program

User · Answer

Append this string to your command    amp - 2  amp -  lt  amp -  amp     amp - means close stdout  2  amp - means close stderr   lt  amp - means close stdin   amp  means run in the background  This works to programmatically start a job via ssh  too     ssh myhost  sleep 30  gt  amp - 2 gt  amp -  lt  amp -  amp     ssh returns right away  and your sleep job is running remotely

User · Answer

I used screen command  This link has detail as to how to do this  https   www rackaid com blog linux-screen-tutorial-and-how-to  starting

User · Answer

nohup blah  amp    Substitute your process name for blah

User · Answer

I would recommend using GNU Screen   It allows you to disconnect from the server while all of your processes continue to run   I don t know how I lived without it before I knew it existed

User · Answer

Append this string to your command    amp - 2  amp -  lt  amp -  amp     amp - means close stdout  2  amp - means close stderr   lt  amp - means close stdin   amp  means run in the background  This works to programmatically start a job via ssh  too     ssh myhost  sleep 30  gt  amp - 2 gt  amp -  lt  amp -  amp     ssh returns right away  and your sleep job is running remotely

User · Answer

When the session is closed the process receives the SIGHUP signal which it is apparently not catching   You can use the nohup command when launching the process or the bash built-in command disown -h after starting the process to prevent this from happening    gt  help disown disown  disown  -h   -ar   jobspec           By default  removes each JOBSPEC argument from the table of active jobs      If the -h option is given  the job is not removed from the table  but is     marked so that SIGHUP is not sent to the job if the shell receives a     SIGHUP   The -a option  when JOBSPEC is not supplied  means to remove all     jobs from the job table  the -r option means to remove only running jobs

User · Answer

Check out the  nohup  program

User · Answer

Check out the  nohup  program

User · Answer

i would also go for screen program  i know that some1 else answer was screen but this is a completion   not only the fact that  amp   ctrl z bg disown  nohup  etc  may give you a nasty surprise that when you logoff job will still be killed  i dunno why  but it did happened to me  and it didn t bother with it be cause i switched to use screen  but i guess anthonyrisinger solution as double forking would solve that   also screen have a major advantage over just back-grounding   screen will background your process without losing interactive control to it   and btw  this is a question i would never ask in the first place        i use screen from my beginning of doing anything in any unix     i  almost  NEVER work in a unix linux shell without starting screen first     and i should stop now  or i ll start an endless presentation of what good screen is and what can do for ya     look it up by yourself  it is worth it

User · Answer

nohup blah  amp    Substitute your process name for blah

User · Answer

I would recommend using GNU Screen   It allows you to disconnect from the server while all of your processes continue to run   I don t know how I lived without it before I knew it existed

User · Answer

On a Debian-based system  on the remote machine  Install   sudo apt-get install tmux  Usage   tmux run commands you want  To rename session   Ctrl B then   set Name  To exit session   Ctrl B then D   this leaves the tmux session   Then  you can log out of SSH  When you need to come back check on it again  start up SSH  and enter  tmux attach session name  It will take you back to your tmux session

User · Answer

As others have noted  to run a process in the background so that you can disconnect from your SSH session  you need to have the background process properly disassociate itself from its controlling terminal - which is the pseudo-tty that the SSH session uses   You can find information about daemonizing processes in books such as Stevens   Advanced Network Program  Vol 1  3rd Edn  or Rochkind s  Advanced Unix Programming    I recently  in the last couple of years  had to deal with a recalcitrant program that did not daemonize itself properly   I ended up dealing with that by creating a generic daemonizing program - similar to nohup but with more controls available   Usage  daemonize  -abchptxV  -d dir  -e err  -i in  -o out  -s sigs  -k fds  -m umask  -- command  args       -V          print version and exit   -a          output files in append mode  O APPEND    -b          both output and error go to output file   -c          create output files  O CREAT    -d dir      change to given directory   -e file     error file  standard error -  dev null    -h          print help and exit   -i file     input file  standard input -  dev null    -k fd-list  keep file descriptors listed open   -m umask    set umask  octal    -o file     output file  standard output -  dev null    -s sig-list ignore signal numbers   -t          truncate output files  O TRUNC    -p          print daemon PID on original stdout   -x          output files must be new  O EXCL    The double-dash is optional on systems not using the GNU getopt   function  it is necessary  or you have to specify POSIXLY CORRECT in the environment  on Linux etc   Since double-dash works everywhere  it is best to use it   You can still contact me  firstname dot lastname at gmail dot com  if you want the source for daemonize   However  the code is now  finally  available on GitHub in my SOQ  Stack Overflow Questions  repository as file daemonize-1 10 tgz in the packages sub-directory

User · Answer

If you re willing to run X applications as well - use xpra together with  screen

User · Answer

Nohup allows a client process to not be killed if a the parent process is killed  for argument when you logout   Even better still use   nohup  bin sh -c  echo       gt   pidfile  exec  FOO BIN  FOO CONFIG     gt   dev null   Nohup makes the process you start immune to termination which your SSH session and its child processes are kill upon you logging out   The command i gave provides you with a  way you can store the pid of the application in a pid file so that you can correcly kill it later and allows the process to run after you have logged out

User · Answer

Accepted answer suggest using nohup  I would rather suggest using pm2  Using pm2 over nohup has many advantages  like keeping the application alive  maintain log files for application and lot more other features  For more detail check this out    To install pm2 you need to download npm  For Debian based system  sudo apt-get install npm   and for Redhat    sudo yum install npm   Or you can follow these instruction  After installing npm use it to install pm2    npm install pm2 latest -g   Once its done you can start your application by      pm2 start app js                Start  Daemonize and auto-restart application  Node    pm2 start app py                Start  Daemonize and auto-restart application  Python    For process monitoring use following commands       pm2 list                        List all processes started with PM2   pm2 monit                       Display memory and cpu usage of each app   pm2 show  app-name              Show all informations about application   Manage processes using either app name or process id or manage all processes together       pm2 stop      lt app name id  all  json conf gt    pm2 restart   lt app name id  all  json conf gt    pm2 delete    lt app name id  all  json conf gt    Log files can be found in     HOME  pm2 logs  contain all applications logs     Binary executable files can also be run using pm2  You have to made a change into the jason file  Change the  exec interpreter     node   to  exec interpreter     none    see the attributes section      include  lt stdio h gt   include  lt unistd h gt     No standard C library int main void        printf  Hello World n        sleep  100       printf  Hello World n         return 0      Compiling above code    gcc -o hello hello c     and run it with np2 in the background    pm2 start   hello

User · Answer

Nohup allows a client process to not be killed if a the parent process is killed  for argument when you logout   Even better still use   nohup  bin sh -c  echo       gt   pidfile  exec  FOO BIN  FOO CONFIG     gt   dev null   Nohup makes the process you start immune to termination which your SSH session and its child processes are kill upon you logging out   The command i gave provides you with a  way you can store the pid of the application in a pid file so that you can correcly kill it later and allows the process to run after you have logged out

User · Answer

daemonize  nohup  SCREEN   tmux ftw  screen is junk  -   Just do what every other app has done since the beginning -- double fork       exec sleep 30  amp     grep PPid  proc  pgrep sleep  status PPid    1   jobs   disown bash  disown  current  no such job   Bang  Done  -   I ve used this countless times on all types of apps and many old machines  You can combine with redirects and whatnot to open a private channel between you and the process   Create as coproc sh      bin bash  IFS   run in coproc          echo  coproc  1  - gt  main      read -r  echo  REPLY      dynamic-coprocess-generator  nice   coproc          local i o e n   1    A-Za-z0-9     shift     exec  i  lt  gt   lt      o  lt  gt   gt      e  lt  gt   gt        dev stdin  lt  lt COPROC                     amp    lt  amp  i  gt  amp  o 2 gt  amp  e      n    o  i  e   COPROC      pi-rads-of-awesome  for x in  0  5   do      coproc COPROC x run in coproc  x     declare -p COPROC x done  for x in COPROC 0  5   do    dev stdin  lt  lt RUN     read -r -u     x 0    echo   REPLY     echo   x  lt - main   gt  amp     x 1       read -r -u     x 0    echo   REPLY RUN done   and then      coproc sh  declare -a COPROC0    0   21   1   16   2   23    declare -a COPROC1    0   24   1   19   2   26    declare -a COPROC2    0   27   1   22   2   29    declare -a COPROC3    0   30   1   25   2   32    declare -a COPROC4    0   33   1   28   2   35    declare -a COPROC5    0   36   1   31   2   38    coproc 0  - gt  main COPROC0  lt - main coproc 1  - gt  main COPROC1  lt - main coproc 2  - gt  main COPROC2  lt - main coproc 3  - gt  main COPROC3  lt - main coproc 4  - gt  main COPROC4  lt - main coproc 5  - gt  main COPROC5  lt - main   And there you go  spawn whatever   the  lt     opens an anonymous pipe via process substitution  which dies  but the pipe sticks around because you have a handle to it  I usually do a sleep 1 instead of   because its slightly racy  and I d get a  file busy  error -- never happens if a real command is ran  eg  command true    heredoc sourcing       dev stdin  lt  lt EOF       EOF   This works on every single shell I ve ever tried  including busybox etc  initramfs    I ve never seen it done before  I independently discovered it while prodding  who knew source could accept args  But it often serves as a much more manageable form of eval  if there is such a thing

User · Answer

I would recommend using GNU Screen   It allows you to disconnect from the server while all of your processes continue to run   I don t know how I lived without it before I knew it existed

User · Answer

Use screen  It is very simple to use and works like vnc for terminals  http   www bangmoney org presentations screen html

User · Answer

i would also go for screen program  i know that some1 else answer was screen but this is a completion   not only the fact that  amp   ctrl z bg disown  nohup  etc  may give you a nasty surprise that when you logoff job will still be killed  i dunno why  but it did happened to me  and it didn t bother with it be cause i switched to use screen  but i guess anthonyrisinger solution as double forking would solve that   also screen have a major advantage over just back-grounding   screen will background your process without losing interactive control to it   and btw  this is a question i would never ask in the first place        i use screen from my beginning of doing anything in any unix     i  almost  NEVER work in a unix linux shell without starting screen first     and i should stop now  or i ll start an endless presentation of what good screen is and what can do for ya     look it up by yourself  it is worth it

User · Answer

If you use screen to run a process as root  beware of the possibility of privilege elevation attacks  If your own account gets compromised somehow  there will be a direct way to take over the entire server   If this process needs to be run regularly and you have sufficient access on the server  a better option would be to use cron the run the job  You could also use init d  the super daemon  to start your process in the background  and it can terminate as soon as it s done

User · Answer

If you use screen to run a process as root  beware of the possibility of privilege elevation attacks  If your own account gets compromised somehow  there will be a direct way to take over the entire server   If this process needs to be run regularly and you have sufficient access on the server  a better option would be to use cron the run the job  You could also use init d  the super daemon  to start your process in the background  and it can terminate as soon as it s done

User · Answer

When the session is closed the process receives the SIGHUP signal which it is apparently not catching   You can use the nohup command when launching the process or the bash built-in command disown -h after starting the process to prevent this from happening    gt  help disown disown  disown  -h   -ar   jobspec           By default  removes each JOBSPEC argument from the table of active jobs      If the -h option is given  the job is not removed from the table  but is     marked so that SIGHUP is not sent to the job if the shell receives a     SIGHUP   The -a option  when JOBSPEC is not supplied  means to remove all     jobs from the job table  the -r option means to remove only running jobs

User · Answer

On systemd Linux  systemd-run is a nice tool to launch session-independent processes

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daemonize  nohup  SCREEN   tmux ftw  screen is junk  -   Just do what every other app has done since the beginning -- double fork       exec sleep 30  amp     grep PPid  proc  pgrep sleep  status PPid    1   jobs   disown bash  disown  current  no such job   Bang  Done  -   I ve used this countless times on all types of apps and many old machines  You can combine with redirects and whatnot to open a private channel between you and the process   Create as coproc sh      bin bash  IFS   run in coproc          echo  coproc  1  - gt  main      read -r  echo  REPLY      dynamic-coprocess-generator  nice   coproc          local i o e n   1    A-Za-z0-9     shift     exec  i  lt  gt   lt      o  lt  gt   gt      e  lt  gt   gt        dev stdin  lt  lt COPROC                     amp    lt  amp  i  gt  amp  o 2 gt  amp  e      n    o  i  e   COPROC      pi-rads-of-awesome  for x in  0  5   do      coproc COPROC x run in coproc  x     declare -p COPROC x done  for x in COPROC 0  5   do    dev stdin  lt  lt RUN     read -r -u     x 0    echo   REPLY     echo   x  lt - main   gt  amp     x 1       read -r -u     x 0    echo   REPLY RUN done   and then      coproc sh  declare -a COPROC0    0   21   1   16   2   23    declare -a COPROC1    0   24   1   19   2   26    declare -a COPROC2    0   27   1   22   2   29    declare -a COPROC3    0   30   1   25   2   32    declare -a COPROC4    0   33   1   28   2   35    declare -a COPROC5    0   36   1   31   2   38    coproc 0  - gt  main COPROC0  lt - main coproc 1  - gt  main COPROC1  lt - main coproc 2  - gt  main COPROC2  lt - main coproc 3  - gt  main COPROC3  lt - main coproc 4  - gt  main COPROC4  lt - main coproc 5  - gt  main COPROC5  lt - main   And there you go  spawn whatever   the  lt     opens an anonymous pipe via process substitution  which dies  but the pipe sticks around because you have a handle to it  I usually do a sleep 1 instead of   because its slightly racy  and I d get a  file busy  error -- never happens if a real command is ran  eg  command true    heredoc sourcing       dev stdin  lt  lt EOF       EOF   This works on every single shell I ve ever tried  including busybox etc  initramfs    I ve never seen it done before  I independently discovered it while prodding  who knew source could accept args  But it often serves as a much more manageable form of eval  if there is such a thing

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