3

From the ps man page:

By default, ps selects all processes with the same effective user ID (euid=EUID) as the current user and associated with the same terminal as the invoker.

On my Ubuntu system, ps without any flags gives the output below, which is as expected:

$ ps
  PID TTY          TIME CMD
 6444 pts/11   00:00:00 bash
14605 pts/11   00:00:00 ps

Now again from the ps man page in OUTPUT MODIFIERS:

e      Show the environment after the command.

But when I try ps e, I get a lot more processes listed:

$ ps e
  PID TTY      STAT   TIME COMMAND
   85 pts/1    Ss+    0:00 -bash HOSTTYPE=x86_64 LANG=C.UTF-8 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:
  100 pts/2    Ss+    0:00 -bash HOSTTYPE=x86_64 LANG=C.UTF-8 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:
  115 pts/3    Ss+    0:00 -bash HOSTTYPE=x86_64 LANG=C.UTF-8 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:
  130 pts/4    Ss+    0:00 -bash HOSTTYPE=x86_64 LANG=C.UTF-8 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:
  146 pts/5    Ss+    0:00 -bash HOSTTYPE=x86_64 LANG=C.UTF-8 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:
  174 pts/6    Ss+    0:00 -bash HOSTTYPE=x86_64 LANG=C.UTF-8 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:
 2988 pts/9    Ss     0:01 -bash HOSTTYPE=x86_64 LANG=C.UTF-8 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:
 3477 pts/9    S+     0:00 vi stepniak.json SHELL=/bin/bash WSL_DISTRO_NAME=Ubuntu-20.04 WT_SESSION=55c420c4-12cf-4f4c-b957-b0b42e2777b8 JAVA_HOME=/home/myr
 4513 pts/0    Ss+    0:02 -bash HOSTTYPE=x86_64 LANG=C.UTF-8 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:
 4540 pts/7    Ss+    0:00 -bash HOSTTYPE=x86_64 LANG=C.UTF-8 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:
 5653 pts/10   Ss+    0:01 -bash HOSTTYPE=x86_64 LANG=C.UTF-8 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:
 6444 pts/11   Ss     0:00 -bash HOSTTYPE=x86_64 LANG=C.UTF-8 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:
 7942 pts/12   Ss     0:00 -bash HOSTTYPE=x86_64 LANG=C.UTF-8 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:
17962 pts/12   Sl     0:03 /home/myroot/jdk-11.0.2/bin/java -classpath /mnt/c/k8s-developer/maven-3.6.3/boot/plexus-classworlds-2.6.0.jar -Dclassworlds.conf
17997 pts/11   R+     0:00 ps e SHELL=/bin/bash WSL_DISTRO_NAME=Ubuntu-20.04 WT_SESSION=7e85f66b-c77a-42da-8782-c0912c196b46 JAVA_HOME=/home/myroot/jdk-11.0
24958 pts/12   Sl     1:05 java -jar myapp.jar SHELL=/bin/bash WSL_DISTRO_NAME=Ubuntu-20.04 WT_SESSION=d9a61855-27fe-4757-a7c9-a38f38fe7fc7 JAVA
25185 pts/12   S+     0:03 tail -f nohup.out SHELL=/bin/bash WSL_DISTRO_NAME=Ubuntu-20.04 WT_SESSION=d9a61855-27fe-4757-a7c9-a38f38fe7fc7 JAVA_HOME=/home/my

From my understanding, e is an OUTPUT modifier and it should not change the criteria used for selecting the processes (which is typically done with -e, a, etc.).

So why is ps e listing more processes than ps?

Note: ps -f or ps -F work as expected -

$ ps -F
UID        PID  PPID  C    SZ   RSS PSR STIME TTY          TIME CMD
myroot    6444  6443  0  4333 12404   2 00:25 pts/11   00:00:00 -bash
myroot   19976  6444  0  2655  3340   7 23:05 pts/11   00:00:00 ps -F

My OS info:

$ cat /etc/*rel*
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=20.04
DISTRIB_CODENAME=focal
DISTRIB_DESCRIPTION="Ubuntu 20.04.3 LTS"
NAME="Ubuntu"
VERSION="20.04.3 LTS (Focal Fossa)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 20.04.3 LTS"
VERSION_ID="20.04"
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
VERSION_CODENAME=focal
UBUNTU_CODENAME=focal
terdon
  • 242,166
samshers
  • 678

1 Answers1

5

ps e uses a BSD-style option (following the procps nomenclature), and this

will also change the process selection to include processes on other terminals (TTYs) that are owned by you

The e option itself doesn’t change the selection, but it changes to a mode where the default selection includes all your processes on the current and other terminals.

The other BSD-style output-controlling options have the same effect; see for example ps l or ps u.

Stephen Kitt
  • 434,908