Bsrgvty

This isn't a problem, more a question of curiosity. When I open Atom editor from the command line using atom it opens in the background. (So I'm returned to the command prompt right away in the terminal.) Typically, if I open an application on the command line using applicationname it would be in the foreground. If I wanted to run it in the background, which I usually do, I'd provide applicationname & instead.

Why don't I have to do atom &?

Like I said, this isn't a problem since I usually want to continue working in the same directory, but I'm curious as to the why.

$ file $(which atom)
/usr/bin/atom: Bourne-Again shell script, ASCII text executable/usr/bin/atom: Bourne-Again shell script, ASCII text executable

You don’t have to start atom in the background because this command doesn’t start the atom process directly, but rather just a starter script. The /usr/bin/atom script evaluates CLI options and sets a bunch of variables before starting the real atom process in a background subshell, see line 180 et seq. (comments mine):

# start a subshell in the background (note “&” below!)
(
# start the Atom process with the current script’s PID redirecting its output to nohup.out
nohup "$ATOM_PATH" --executed-from="$(pwd)" --pid=$$ "$@" > "$ATOM_HOME/nohup.out" 2>&1
# in case of any error, print the output and exit
if [ $? -ne 0 ]; then
 cat "$ATOM_HOME/nohup.out"
 exit $?
fi
) &

Let’s see which file is the real atom executable started here:

• 
  

  it starts $ATOM_PATH, which is set on line 163:

  
  
  

  ATOM_PATH="$USR_DIRECTORY/share/atom/atom"
  

  
  


• 
  

  $USR_DIRECTORY is set on line 150:

  
  
  

  USR_DIRECTORY=$(readlink -f $(dirname $SCRIPT)/..)
  

  
  
  

  This equals:

  
  
  

  USR_DIRECTORY=$(readlink -f $(dirname /usr/bin/atom)/..) # equals
  USR_DIRECTORY=$(readlink -f /usr/bin/..) # equals
  USR_DIRECTORY=$(readlink -f /usr) # equals
  USR_DIRECTORY=/usr
  

  
  

Now we have the full path to the atom executable: /usr/share/atom/atom. The output of file confirms that:

$ file /usr/share/atom/atom
/usr/share/atom/atom: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/l, for GNU/Linux 2.6.32, stripped