I need to troubleshoot some problems related to environment variables on a Unix system.
On Windows, I can use a tool such as ProcessExplorer to select particular a process and view values of each environment variable.
How can I accomplish the same thing on Unix? echoing and env cmd just show values at present time, but I want to view what values the running process is using currently.
cat /proc/<pid>/environ
If you want to have pid(s) of a given running executable you can, among a number of other possibilities, use pidof:
AlberT$ pidof sshd
30690 6512
EDIT:
I totally quote Dennis Williamson and Teddy comments to achieve a more readable output. My solution is the following:
tr '\0' '\n' < /proc/<pid>/environ
cat /proc/17330/environ | tr \\0 \\n
Sep 17, 2009 at 19:14
xargs to convert nulls to newlines is better than using tr. Can someone lay it out for me? Thanks.
May 9, 2017 at 13:55
Since this question has a unix tag and everyone else has done such a great job addressing linux tag, you can get this information on OS X and other BSD-derived systems using
ps -p <PID> -wwwe
or
ps -p <PID> -wwwE
and on Solaris with
/usr/ucb/ps -wwwe <PID>
Solaris also supports the /proc directory if you don't want to remember the obscure ps commmand.
ps -p <PID> -wwE.
/proc/PID/environ. Those files are only readable by the owner of the process.
May 9, 2017 at 13:58
As others have mentioned, on Linux, you can look in /proc but there are, depending on your kernel version, one or two limits:
First of all, the environ file contains the environment as it looked when the process was spawned. That means that any changes the process might have made to its environment will not be visible in /proc:
$ cat /proc/$$/environ | wc -c
320
$ bash
$ cat /proc/$$/environ | wc -c
1270
$
The first shell is a login shell and initially has a very limited environment but grows it by sourcing e.g. .bashrc but /proc does not reflect this. The second shell inherits the larger environment from the start, which it why it shows in /proc.
Also, on older kernels, the contents of the environ file is limited to a page size (4K):
$ cat /proc/$$/environ | wc -c
4096
$ env | wc -c
10343
$
Somewhere between 2.6.9 (RHEL4) and 2.6.18 (RHEL5) this limit was removed...
correct usage of BSD options to do this (at least on linux):
ps e $pid
or
ps auxe #for all processes
and yes, ps manpage is pretty confusing. (via)
ps eww $pid fixes the 2nd problem.
Dec 3, 2013 at 14:42
xargs or tr to convert these to newlines for readability. You probably realised this in the intervening four years.
May 9, 2017 at 14:01
While rather sparsely documented, the contents of /proc/<pid>/environ will only contain the environment that was used to start the process.
If you need to inspect the current state of a process' environment, one way to do that is by using gdb.
# Start gdb by attaching it to a pid or core file
gdb <executable-file> <pid or core file>
# Run the following script to dump the environment
set variable $foo = (char **) environ
set $i = 0
while ($foo[$i] != 0)
print $foo[$i++]
end
quit command in the end into a .gdb file, such as ~/penv.gdb; then starts gdb(1) with this GDB script any time when you want to exam the environment of a process, by running gdb -x ~/penv.gdb -p <pid> [<exe-file>].
Nov 29, 2019 at 4:41
cat /proc/PID/environ
replace PID with the PID of the process you want to see. Every information about a running process is under /proc/PID/ directory
example: cat /proc/32512/environ
Taken from the Archlinux wiki:
You can create a temporary function to parse the values in /proc/<pid>/environ. At the terminal prompt:
envof() { sed 's/\x0/\n/g' /proc/${1}/environ; }
Then with the pid of the process you want, just use:
envof <pid>
Under Linux, I'd try having a look at
/proc/<pid>/environ
For Solaris 5.10, this works:
pargs -e <PID>
And since my job makes me be an AIX fan boy, let us not forget:
ps eww [pid]
Or as the man page calls it, "Berkeley Standards".
For whatever reason, /proc/PID/environ does not exist in AIX.
If you want to create formatted env like output of the environment variables for an arbitrary process (PID), you can create a convenient bash penv <pid> command (tailored to your OS) and add it to your .bashrc:
Linux add this to your ~/.bashrc:
penv () {
xargs --null --max-args=1 < /proc/$1/environ
}
macOS / BSD add this to your ~/.bashrc:
penv() {
ps eww -o command $1 | tr ' ' '\n'
}
Solaris add this to your ~/.bashrc:
penv() {
pargs -e $1
}
Usage:
$ source $HOME/.bashrc $ pgrep VBoxSVC 10268 $ penv 10268 SSH_CONNECTION=1.1.1.242 53960 1.1.1.91 22 GREP_COLORS=sl=49;39:cx=49;39:mt=49;38;5;167;1:fn=49;39;1:ln=49;39:bn=49;39:se=50;39 LANG=en_US.UTF-8 EDITOR=vim XDG_SESSION_ID=106 USER=root PWD=/root HOME=/root SSH_CLIENT=1.1.1.242 53960 22 SSH_TTY=/dev/pts/3 MAIL=/var/mail/root TERM=xterm-256color SHELL=/bin/bash SHLVL=1 LOGNAME=root DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/0/bus XDG_RUNTIME_DIR=/run/user/0 PATH=/root/bin:/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:. VBOX_LOG_FLAGS=thread tsc VBOX_LOG=-all+dev_vmm_backdoor.e.l.f+dev_vmm.e.l.f
A mac solution, probably other BSDs as well could be something like
pid=28369; ps e $pid | cut -c$(expr 1 + $(ps p $pid|tail +2|wc -c))-
The environment variables are appended to the command line, this removes the command line and we only have the environment variables left.
It is not perfect because they are space separated not LF separated
/proc/PID/environ
for this, first we need to identify the PID of the process. for this you can use ps command
