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 $SLACK_LEGACY_API_TOKEN?
As mentioned by #chepner in the comments within my question, the issue was caused by defining the .sh file in my Windows environment. This results in the file being saved with DOS line endings which was causing the issues with the script. Redefining the file entirely within the Linux environment solved the problem.
Related
When creating Bash scripts, I have always had a line right at the start defining the PATH environment variable. I recently discovered that this doesn't make the script very portable as the PATH variable is different for different versions of Linux (in my case, I moved the script from Arch Linux to Ubuntu and received errors as various executables weren't in the same places).
Is it possible to copy the PATH environment variable defined by the login shell into the current Bash script?
EDIT:
I see that my question has caused some confusion resulting in some thinking that I want to change the PATH environment variable of the login shell with a bash script, which is the exact opposite of what I want.
This is what I currently have at the top of one of my Bash scripts:
#!/bin/bash
PATH=/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl
# Test if an internet connection is present
wget -O /dev/null google.com
I want to replace that second line with something that copies the value of PATH from the login shell into the script environment:
#!/bin/bash
PATH=$(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
My teacher gave us this assignment to create our own shell. Our shell is supposed be called rshell and is supposed to work like the regular shell.
I created my own shell using C++. If you type a command like ls in my created shell it gives you a list just like how if you typed ls in the regular shell.
The problem I am facing is how do I get the .sh files or script files to work with my created shell. I noticed when I run a .sh file using my shell it does not run the .sh file through my shell. It runs it through the regular shell. How do I make .sh files run through my shell?
Change the hash-bang line of the scripts to point at your shell. For instance,
#!/usr/local/bin/rshell
Or wherever your shell executable is.
As John already said, change the shebang to point to your shell. The kernel will invoke the command in the shebang with the file itself as an argument. To demonstrate, try a file with a shebang of #!/bin/cat.
#!/bin/cat
hello world
It pretty much behaves the same as if you typed /bin/cat /path/to/file.
The shebang does not have PATH lookup capabilities, so #!yourshell would not work as a shebang. However, you can use env to do the PATH lookup as in #!/usr/bin/env yourshell. (This approach is preferred for commands that are at different paths on different systems, like python.)
In order to run a Tcl script on Linux, I need to set the environment variable "$LD_LIBRARY_PATH" each time.
For convenience, I develop a shell script to do this.Currently, on my own server, if I type
echo $LD_LIBRARY_PATH
the result is:
/opt/lsf/9.1/linux2.6-glibc2.3-x86_64/lib
so in my shell script I write the following code:
export LD_LIBRARY_PATH="/opt/lsf/9.1/linux2.6-glibc2.3-x86_64/lib:$INSTALL_ROOT/tcl_tk/lib64:$INSTALL_ROOT/tcl_tk/lib64"
where the "$INSTALL_ROOT/tcl_tk/lib64:$INSTALL_ROOT/tcl_tk/lib64" part is what I want to add. It works well. Now the issue is:
If I want to run the script on any server, so the original "$LD_LIBRARY_PATH" will be different, based on my understanding. So how to make it flexible on any server?
I try this in my shell script:
export LD_LIBRARY_PATH="$LD_LIBRARY_PATH:$INSTALL_ROOT/tcl_tk/lib64:$INSTALL_ROOT/tcl_tk/lib64"
But not so sure,
I am new to system stuffs, need some help. Hope explain the issue clearly.
If your default shell is bash, i would define the variables in ~/.bashrc like:
export INSTALL_ROOT=...##assuming a lready defined
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$INSTALL_ROOT/tcl_tk/lib64:$INSTALL_ROOT/tcl_tk/lib64
So in this way, you dont have to worry anything about setting variables in multiple shell scripts as this .bashrc is going to setup variable for you beforehand.
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.
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.