Currently I'm setting up a new system using the new Xubuntu trusty tahr.
I'm not very familiar with shell scripting, but I have one which needs the OSTYPE environment variable to determine what to do.
If I call echo $OSTYPE in the xfce-terminal I get succesfully linux-gnu.
If I call following script I only get an empty line.
#!/bin/sh
echo $OSTYPE
Am I missing something or is it maybe a problem of the new ubuntu?
On another machine of mine it works with that script. But I don't know if something was changed for that, because the system was originally not mine.
The OSTYPE environment variable is not recognized by the original Bourne shell, which is what is being invoked by the first line of your script.
Replace it with:
#!/bin/bash
or
#!/bin/ksh
as appropriate to your setup.
Related
I'm running Ubuntu on Windows Subsystem for Linux, and I have a bash script that I want to run that needs to access system environment variables. Specifically, I defined an environment variable on my system with the following command:
export SLACK_LEGACY_API_TOKEN="Insert Token Here"
I then define a file called slack.sh that looks like this:
#!/usr/bin/env bash
echo $SLACK_LEGACY_API_TOKEN
I then run this script with source ./slack.sh. When I run this command, it just prints out a blank line - it's not getting the value of the environment variable.
I've tried different syntax in the .sh file for referencing the environment variable, like "$SLACK_LEGACY_API_TOKEN" and ${SLACK_LEGACY_API_TOKEN} but same result. I've also run the script with /slack.sh and . ./slack.sh but same results.
How do I get my script to see $SLACK_LEGACY_API_TOKEN?
As mentioned by #chepner in the comments within my question, the issue was caused by defining the .sh file in my Windows environment. This results in the file being saved with DOS line endings which was causing the issues with the script. Redefining the file entirely within the Linux environment solved the problem.
This question already has answers here:
How to get the default shell
(5 answers)
Closed 6 years ago.
I am composing a bash script to serve as a utility tools.
The challenges I am facing now is:
- user using my tool will be running in bash environment
- however, some of them might default using krcsh or tcsh. they might have aliases or configurations set in there.
So, I need to prompt/guide user to resolve this during installation. My first challenge: How am I suppose to know the user's default shell within my install.sh?
Knowing the "default" shell, I can prompt and guide the user to do necessary transfer to bash.
my testing code:
my result:
1/ is fault obviously. It return the current shell which is my install.sh (bash)
2/ I am doubtful. It seems to be the history of what I have run before. It does not show me my default configured shell. My case, my terminal default shell is bash, and I run tsch for testing purpose. So the script parsed wrong information and will though my default shell is tcsh. It will then assist me to port configurations from tcsh to bash during the installation process.
If you want to check the shell you are using, you can use the following methods:
echo $0 in terminal will show you the program running if you want to check the shell you are currently using.
echo $SHELL - with this command you can read the user's default shell in the terminal you are running.
If you want to prompt, easily you can put the echo $SHELL in the part of your script where you need to show the current shell you are using.
Don't forget to put #!/bin/bash if your script is designed to run in a bash shell!
While the man for env on Linux seems to indicate that you can set new environment variables before executing a command. Unfortunately, when I set new variables in a file's shebang on Linux systems, the file never executes.
#!/usr/bin/env VAR1=foo bash
echo $VAR1
When I execute this file on a CentOS or Ubuntu machine, it just sits there.
$ ./shell-env.sh
<nothing happens>
What I find particularly bizarre is this works perfectly fine on OS X with BSD env.
$ ./shell-env.sh
foo
$
Is this just a difference between BSD env and Linux env? Why do the man pages for Linux seem to say it should work the same way as on BSD?
P.S. My use case here is to override the PATH variable, so I can try to find a ruby on the system but that's not on the PATH.
Thank you in advance!
There's a way to manipulate the environment before executing a Ruby script, without using a wrapper script of some kind, but it's not pretty:
#!/bin/bash
export FOO=bar
exec ruby -x "$0" "$#"
#!ruby
puts ENV['FOO']
This is usually reserved for esoteric situations where you need to manipulate e.g. PATH or LD_LIBRARY_PATH before executing the program, and it needs to be self-contained for some reason. It works for Perl and possibly others too!
When creating Bash scripts, I have always had a line right at the start defining the PATH environment variable. I recently discovered that this doesn't make the script very portable as the PATH variable is different for different versions of Linux (in my case, I moved the script from Arch Linux to Ubuntu and received errors as various executables weren't in the same places).
Is it possible to copy the PATH environment variable defined by the login shell into the current Bash script?
EDIT:
I see that my question has caused some confusion resulting in some thinking that I want to change the PATH environment variable of the login shell with a bash script, which is the exact opposite of what I want.
This is what I currently have at the top of one of my Bash scripts:
#!/bin/bash
PATH=/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl
# Test if an internet connection is present
wget -O /dev/null google.com
I want to replace that second line with something that copies the value of PATH from the login shell into the script environment:
#!/bin/bash
PATH=$(command that copies value of PATH from login shell)
# Test if an internet connection is present
wget -O /dev/null google.com
EDIT 2: Sorry for the big omission on my part. I forgot to mention that the scripts in question are being run on a schedule through cron. Cron creates it's own environment for running the scripts which does not use the environment variables of the login shell or modify them. I just tried running the following script in cron:
#!/bin/bash
echo $PATH >> /home/user/output.txt
The result is as follows. As you can see, the PATH variable used by cron is different to the login shell:
user#ubuntu_router:~$ cat output.txt
/usr/bin:/bin
user#ubuntu_router:~$ echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
Don't touch the user's PATH at all unless you have a specific reason. Not doing anything will (basically) accomplish what you ask.
You don't have to do anything to get the user's normal PATH since every process inherits the PATH and all other environment variables automatically.
If you need to add something nonstandard to the PATH, the usual approach is to prepend (or append) the new directory to the user's existing PATH, like so:
PATH=/opt/your/random/dir:$PATH
The environment of cron jobs is pretty close to the system's "default" (for some definition of "default") though interactive shells may generally run with a less constrained environment. But again, the fix for that is to add any missing directories to the current value at the beginning of the script. Adding directories which don't exist on this particular system is harmless, as is introducing duplicate directories.
I've managed to find the answer to my question:
PATH=$PATH:$(sed -n '/PATH=/s/^.*=// ; s/\"//gp' '/etc/environment')
This command will grab the value assigned to PATH by Linux from the environment file and append it to the PATH used by Cron.
I used the following resources to help find the answer:
How to grep for contents after pattern?
https://help.ubuntu.com/community/EnvironmentVariables#System-wide_environment_variables
I am using anaconda python. So every time, in my mac terminal, I input the terminal command:
source /Users/mylaptop/anaconda/bin/activate /Users/mylaptop/anaconda
And then I activated the anaconda python environment. But I don't want to write this command line every time, so I tried a bash script like this:
#! /bin/bash
source /Users/mylaptop/anaconda/bin/activate /Users/mylaptop/anaconda
and I put this file in the directory /usr/local/bin. But unfortunately, I cannot log into anaconda environment in this way. There is no error message showed up in the terminal. So I do not know what is happening here.
Could anyone help me out?
The easiest fix is to just put /Users/mylaptop/anaconda in your PATH, by adding something like
export PATH="/Users/mylaptop/anaconda:$PATH"
to your bash profile (~/.profile).
You can't put the activate script in a script because it has to be "sourced" to work. source causes the script to be run in your current shell (as opposed to a subshell, which is how the bash script you wrote is run). This is necessary because it modifies your PATH environment variable, and environment variables from your current shell cannot be modified by subshells.