I am running a korn shell script as root and need to sudo to a different user (oracle) to execute some commands and I need access to the environment variables set in .profile.
I am seeing different behavior if I call a 2nd script to execute the commands versus executing them inline.
Here is a simple test to demonstrate. This works and displays the $ORACLE_HOME environment variable:
sudo su - oracle -s /bin/ksh -c "/home/u6vzbes/upgrade/get_oracle_home_test.ksh"
Where the called script is just this:
#!/bin/ksh
echo 'Called from script - ORACLE_HOME is ' ${ORACLE_HOME}
But this DOES NOT work, with the $ORACLE_HOME environment variable being blank:
sudo su - oracle -s /bin/ksh -c "
echo 'Called from sudo - Oracle home is ${ORACLE_HOME}'
"
Why do these two work differently? I would prefer to execute commands inline rather than have a second script as I will need to sudo to oracle multiple times throughout the root script. FYI, the environment variable is set in the .profile of the oracle user.
The ' escape doesn't work in this case. The following works, escaping the $ character:
sudo su - oracle -s /bin/ksh -c "echo Called from sudo - Oracle home is \${ORACLE_HOME}"
So remove the ' and place \ in front of $
Related
I have a docker container writing logfiles to a name volume.
From the host I want to analyce the logfiles and search for given log messages. But when I access the folder which 'docker inspect VOLUMNAME' gives, I get strange behavior, which I do not understand.
e.g. following command does give empty lines as output:
user#docker-host-01:~/docker-server-env/otaya-designdb$ sudo bash -c "for logfile in /var/lib/docker/volumes/design-db-logs/_data/*/*; do echo ${logfile}; done"
user#docker-host-01:~/docker-server-env/otaya-designdb$
What could be the reason?
Your local shell is expanding the variable expansion inside the double quotes before the loop happens. Change the double quotes to single quotes.
That is, when you run
sudo bash -c "for ... ; do echo ${logfile}; done"
first your local shell replaces the variable reference with whatever your local environment has set for $logfile, probably nothing
sudo bash -c 'for ...; do echo ; done'
and then it runs that command. If you change this to single quotes initially
sudo bash -c 'for ... ; do echo ${logfile}; done'
it will avoid this expansion.
You can see this just by putting the word echo at the front of the command: the shell will do its expansion, and then echo will print out the command that would have run.
I've a simple shell script that executes a docker-exec command inside a container.
The script is located in /var/www/mysite-nginx/nginx-reload.sh and permissions of this file are -rwxrwxr-x
#!/bin/sh
docker exec -it mysite_nginx nginx -s reload
If I execute this script directly from shell, it works. But if I add the script to my crontab with the following line, it doesn't work.
15 4 * * * /var/www/mysite-nginx/nginx-reload.sh
I suppose that cron doesn't execute the command, or what is wrong?
On /var/log/syslog I have:
Jul 23 15:30:01 arrubiu CRON[29511]: (sergej) CMD (/var/www/mysite-nginx/nginx-reload.sh)
[EDIT] Solved in this way: docker exec is not working in cron
The issue seems to be that docker is not found. There are two ways around:
You enter the full paths of all application in your crontab script, you can find that out using e.g. locate docker, so that it looks something like
#!/bin/sh
/usr/bin/docker exec -it mysite_nginx
/usr/bin/nginx -s reload
Alternatively, you can set the $PATH and other environment variables in the same way how they are set for a usual sh-script. To achieve that, first backup what is saved in /etc/environment, and then flush it with the currently available variables by executing:
cp /etc/environment > ~/my_etc_environment_backup
env >> /etc/environment
Related questions on SO
Where can I set environment variables that crontab will use?
If I want to run, for example wget, in a Docker file, I can type this:
RUN wget http://example.com
If I want do an echo command I could do this
RUN echo 'Hello' >> /home/file.text
But I've also seen this:
RUN bash -c 'echo $USERNAME:ros | chpasswd'
If I want to run a shell script, I could do this
RUN 'bash ./install_foo.sh'
I also was recommended this:
RUN . /home/ros/.bashrc
I think there are some invalid examples above and others that have subtle differing semantics. I would like to
Understand it so I can learn
What the right one is to use when I want to run a shell script
Here's a brain dump of related one-line answers:
Every RUN command launches a new shell (in a new container even) with a new clean environment and doesn't read any dotfiles. RUN export ... and RUN . ... are both no-ops that will have no effect on later steps.
Many standard Docker paths (like docker run ... some command) don't involve a shell at all, so if you create a .bashrc or .profile file it will be ignored in many common cases.
Unquoted RUN some command, CMD some command, and ENTRYPOINT some command are all automatically wrapped in sh -c '...' and you basically never need to say this explicitly. (In the case of ENTRYPOINT using the unquoted form is probably a bug.) Forms like CMD ["some", "command"] do not implicitly involve a shell (and don't expand environment variables).
GNU bash has several vendor extensions that unfortunately are in widespread use; Alpine base images don't include bash. In particular never say source when . is in the standard and does the same thing.
If you're installing software in an image, your best choice is to install it in a "system" location (pip install without an active virtual environment, npm install -g, ./configure --prefix=/usr/local); if you must install it somewhere else, use the Dockerfile ENV directive to set any environment variables that are needed; and if you can't do that, an ENTRYPOINT wrapper script can programmatically set the environment for the main process (but not any docker exec shells).
Just in general, ./foo.sh will run a shell script (provided it is executable and starts with a #!/bin/sh line); bash foo.sh will as well (but doesn't require it to be executable and explicitly specifies which shell to use); and . ./foo.sh runs it in the context of the current shell (only this form can change environment variables for example).
How can I run a command on xterm startup i.e. when an xterm terminal is launched a the command is already executed?
I have edited the .bashrc file to add this line:
xterm "ls"
But this does not work.
Please suggest what should I do to acheive this.
Thanks.
According to the bash manual, ~/.bashrc is used for interactive shells. xterm runs a shell, so perhaps your "does not work" causes a chain of xterm's.
The xterm program sets these environment variables which are useful for scripting: XTERM_VERSION and XTERM_SHELL. In your ~/.bashrc file, you could use the former to run the xterm -ls once only:
if [[ -z "$XTERM_VERSION" ]]
then
xterm -hold -e ls &
fi
which seems to be what you are asking for:
it would run an xterm if not run from an existing xterm
it prevents the xterm from closing when the ls is done.
A more useful-seeming way of showing an ls on shell startup would be to run ls in each shell as it is started (for that case, you do not need run a separate xterm). Again, you can use environment variables to do this once (in case you run bash to make a subshell):
if [[ -z "$XTERM_ONCE" ]]
then
export XTERM_ONCE=$(date)
ls
fi
I use this:
-e /bin/bash -login
-e command [arguments]
Run the command with its command-line arguments in the rxvt window;
also sets the window title and icon name to be the basename of the
program being executed if neither -title (-T) nor -n are given on the
command line. If this option is used, it must be the last on the
command-line. If there is no -e option then the default is to run the
program specified by the SHELL environment variable or, failing that,
sh(1).
http://linux.die.net/man/1/rxvt
I want to set $PS1 environment variable to the container. It helps me to identify multilevel or complex docker environment setup. Currently docker container prompts with:
root#container-id#
If I can change it as following , I can identify the container by looking at the $PS1 prompt itself.
[Level-1]root#container-id#
I did experiments by exporting $PS1 by making my own image (Dockerfile), .profile file etc. But it's not reflecting.
I had the same problem but in docker-compose context.
Here is how I managed to make it work:
# docker-compose.yml
version: '3'
services:
my_service:
image: my/image
environment:
- "PS1=$$(whoami):$$(pwd) $$ "
Just pass PS1 value as an environment variable in docker-compose.yml configuration file.
Notice how dollars signs need to be escaped to prevent docker-compose from interpolating values (documentation).
This Dockerfile sets PS1 by doing:
RUN echo 'export PS1="[\u#docker] \W # "' >> /root/.bash_profile
We use a similar technique for tracking inputs and outputs in complex container builds.
https://github.com/ianmiell/shutit/blob/master/shutit_global.py#L1338
This line represents the product of hard-won experience dealing with docker/(p)expect combinations:
"SHUTIT_BACKUP_PS1_%s=$PS1 && PS1='%s' && unset PROMPT_COMMAND"
Backing up the prompt is handy if you want to revert, setting the PS1 with PS1= sets the PS1, and unsetting the PROMPT_COMMAND removes any nasty surprises with the terminal being reset etc.. for the expect.
If the question is about how to ensure it's set when you run the container up (as opposed to building), then you may need to add something to your .bashrc / .profile files depending on how you run up your container. As far as I know there's no way to ensure it with a dockerfile directive and make it persist.
I normally create /home/USER/.bashrc or /root/.bashrc, depending on who the USER of the Dockerfile is. That works well. I've tried
ENV PS1 '# '
but that never worked for me.
Here's a way to set the PS1 when you run the container:
docker run -it \
python:latest \
bash -c "echo \"export PS1='[python:latest] \w$ '\" >> ~/.bashrc && bash"
I made a little wrapper script, to be able to run any image with my custom prompt:
#!/usr/bin/env bash
# ~/bin/docker-run
set -eu
image=$1
docker run -it \
-v $(pwd):/opt/app
-w /opt/app ${image} \
bash -c "echo \"export PS1='[${image}] \w$ '\" >> ~/.bashrc && bash"
In debian 9, for running bash, this worked:
RUN echo 'export PS1="[\$ENV_VAR] \W # "' >> /root/.bashrc
It's generally running as root and I generally know I am in docker, so I wanted to have a prompt that indicated what the container was, so I used an environment variable. And I guess the bash I use loads .bashrc preferentially.
Try setting environment variables using docker options
Example:
docker run \
-ti \
--rm \
--name ansibleserver-debug \
-w /githome/axel-ansible/ \
-v /home/lordjea/githome/:/githome/ \
-e "PS1=DEBUG$(pwd)# " \
lordjea/priv:311 bash
docker --help
Usage: docker run [OPTIONS] IMAGE [COMMAND] [ARG...]
Run a command in a new container
Options:
...
-e, --env list Set environment variables
...
You should set that in .profile, not .bashrc.
Just open .profile from your root or home and replace PS1='\u#\h:\w\$ ' with PS1='\e[33;1m\u#\h: \e[31m\W\e[0m\$ ' or whatever you want.
Note that you need to restart your container.
On my MAC I have an alias named lxsh that will start a bash shell using the ubuntu image in my current directory (details). To make the shell's prompt change, I mounted a host file onto /root/.bash_aliases. It's a dirty hack, but it works. The full alias:
alias lxsh='echo "export PS1=\"lxsh[\[$(tput bold)\]\t\[$(tput sgr0)\]\w]\\$\[$(tput sgr0)\] \"" > $TMPDIR/a5ad217e-0f2b-471e-a9f0-a49c4ae73668 && docker run --rm --name lxsh -v $TMPDIR/a5ad217e-0f2b-471e-a9f0-a49c4ae73668:/root/.bash_aliases -v $PWD:$PWD -w $PWD -it ubuntu'
The below solution assumes that you've used Dockerfile USER to set a non-root Linux user for Bash.
What you might have tried without success:
ENV PS1='[docker]$' ## may not work
Using ENV to set PS1 can fail because the value can be overridden by default settings in a preexisting .bashrc when an interactive shell is started. Some Linux distributions are opinionated about PS1 and set it in an initial .bashrc for each user (Ubuntu does this, for example).
The fix is to modify the Dockerfile to set the desired value at the end of the user's .bashrc -- overriding any earlier settings in the script.
FROM ubuntu:20.04
# ...
USER myuser ## the username
RUN echo "PS1='\n[ \u#docker \w ]\n$ '" >>.bashrc