I need to modify the PATH environment using a script. My script is:
--begin-- #!bin/sh export PATH=$PATH:/mydir --end--
If I run the export command in command line I have no problem, but when I run my script, and I run
echo $PATH
I can see that the path environtment variable isn't changed.
What can be the problem? I'm root user when I run the script.
Thanks
Am Di, den 21.12.2004 schrieb Samuel Díaz García um 23:43:
I need to modify the PATH environment using a script. My script is:
--begin-- #!bin/sh
#!/bin/sh
The leading slash is missing.
export PATH=$PATH:/mydir --end--
If I run the export command in command line I have no problem, but when I run my script, and I run
echo $PATH
I can see that the path environtment variable isn't changed.
What can be the problem? I'm root user when I run the script.
Why root?
Samuel Díaz García
Alexander
No, the leading slash were there, only I mistake at writing the message, sorry.
Samuel Díaz García Director Gerente ArcosCom Wireless, S.L.L.
mailto:samueldg@arcoscom.com http://www.arcoscom.com móvil: 651 93 72 48 tlfn/fax: 956 70 13 15
Alexander Dalloz escribió:
Am Di, den 21.12.2004 schrieb Samuel Díaz García um 23:43:
I need to modify the PATH environment using a script. My script is:
--begin-- #!bin/sh
#!/bin/sh
The leading slash is missing.
export PATH=$PATH:/mydir --end--
If I run the export command in command line I have no problem, but when I run my script, and I run
echo $PATH
I can see that the path environtment variable isn't changed.
What can be the problem? I'm root user when I run the script.
Why root?
Samuel Díaz García
Alexander
Samuel Díaz García kirjoitti viestissään (lähetysaika keskiviikko, 22. joulukuuta 2004 00:43):
I need to modify the PATH environment using a script. My script is:
--begin-- #!bin/sh export PATH=$PATH:/mydir --end--
If I run the export command in command line I have no problem, but when I run my script, and I run
echo $PATH
I can see that the path environtment variable isn't changed.
What can be the problem?
The script is run in a new shell, and the export command has effect only in that shell and any commands started from it. You must use the "source" command to execute the script in the current shell.
Samuel Díaz García wrote:
I need to modify the PATH environment using a script. My script is:
--begin-- #!bin/sh export PATH=$PATH:/mydir --end--
If I run the export command in command line I have no problem, but when I run my script, and I run
echo $PATH
I can see that the path environtment variable isn't changed.
What can be the problem? I'm root user when I run the script.
Try sourcing the script: . scriptname That makes the *current* shell run the commands in the script.
Otherwise, the shell you're typing into will start another shell process to actually run the script. And the change in the PATH variable will only be available to that script and the processes started by that script (and the processes they start, and)...
You should understand that Unix processes are started by a "parent", and may start "child" processes. So your shell's parent might be gnome-terminal, which has a parent of init, which is the ultimate ancestor of all processes on a Unix system.
And child processes *cannot* change their parent's state, including their environment.
(For these purposes, Fedora is an implementation of Unix.)
Hope this helps,
James.
On Tue, Dec 21, 2004 at 11:43:27PM +0100, Samuel Díaz García wrote:
I need to modify the PATH environment using a script. My script is:
--begin-- #!bin/sh export PATH=$PATH:/mydir --end--
If I run the export command in command line I have no problem, but when I run my script, and I run
echo $PATH
I can see that the path environtment variable isn't changed.
What can be the problem? I'm root user when I run the script.
You should not need to be root.
The problem is that variables in the environment are passed from parent to child. Not to the system or from child to parent.
The pseudo comment
#!.bin/sh
instructs exec to fork a child process bin/sh with the input that follows.
export PATH=$PATH:/mydir
The child process has the new environment, not the parent of the process. ps lets you see the partent child relationship. Note how 646 is in different collums below. $ ps -l F S UID PID PPID C PRI NI ADDR SZ WCHAN TTY TIME CMD 0 S 500 646 11293 0 75 0 - 1323 wait pts/2 00:00:00 bash 0 R 500 669 646 0 77 0 - 971 - pts/2 00:00:00 ps
The environment of a process you own/conftol can be seen in the /proc filesystem.
$ ls /proc/646 attr cmdline environ fd mem root statm task auxv cwd exe maps mounts stat status wchan
You can have your child process sleep and then go have a look in the /proc filesystem. #!/bin/sh export PATH=$PATH:/mydir sleep 3600 # about an hour
What you are attempting to do is commonly done in a dot file in the users home directory. $ grep PATH .[a-z]* .bash_profile:PATH=:$HOME/bin:$PATH:.:
Next time you login this will be included as part of the normal start up for a user.
The shell "csh" has a command "source" and bash and sh use the notation . to include shell command in a script. You will see this in /etc/init.d scripts by way of example.
# Source function library if [ -f /etc/init.d/functions ]; then . /etc/init.d/functions elif [ -f /etc/rc.d/init.d/functions ] ; then . /etc/rc.d/init.d/functions else exit 0 fi
You will also see in /etc/bashrc a snip of shell code that picks up commonly used stuff from /etc/profile.d/ for i in /etc/profile.d/*.sh; do if [ -r "$i" ]; then . $i fi done unset i
If you follow this strategy you will find a template for adding stuff to PATH in this /etc/profile.d/krb5.sh that does not keep adding duplicate stuff to $PATH.
Look also at /etc/bashrc where a test for the user id is made. In general you do not want to modify PATH for the root and other system accounts as it opens up a door for trojan horse programs.
-
Alexander Dalloz -
James Wilkinson -
Markku Kolkka -
Samuel Díaz García -
Tom Mitchell