nohup —
invoke a command immune to hangups
The nohup command allows the specified utility to be
  protected from termination if the user should become logged out (for example,
  due to a modem line or TCP/IP connection being dropped). To do this,
  nohup sets the SIGHUP
  signal(3) (“terminal line
  hangup”) to be ignored, then executes utility
  along with any arguments.
If the standard output is a terminal, the standard output is
    appended to the file nohup.out in the current
    directory. If standard error is a terminal, it is directed to the same place
    as the standard output. If the output file nohup.out
    cannot be created in the current directory, nohup
    attempts to create the file in the user's home directory. If the file
    nohup.out cannot be created, either in the current
    directory or the user's home directory, nohup will
    exit without invoking utility, with an exit value as
    described below.
The following variable is used by nohup:
  - HOME
- User's home directory.
Thenohup utility exits with one of the following
  values:
  - 126
- The utility was found but could not be invoked.
- 127
- The utility could not be found or an error occurred
      in nohup.
Otherwise, the exit status of nohup will
    be that of utility.
The nohup command is expected to be
  IEEE Std 1003.2 (“POSIX.2”) compatible.