What does 'export' do when used in a command line.
For example, and this is only one example, I build a number of C++ libraries and for a library such as zlib-1.2.8 I need to specify the install directories.
To do this I need to do the following in MSYS command line interface. This is just one example
export LIBRARY_PATH="c/libraries/libs;$LIBRARY_PATH"
Would anyone know what the command 'export' actually does in this instance?
Does it permanently install a record for MSYS to user later on when looking for dependencies such as ZLIB . My using make install the zlib library file is placed in this directory.
OR, when I close MSYS is this LIBRARY_PATH lost from MSYS memory?
Thanks
This is the bash syntax to set an environment variable. Using export allows the variable to be seen outside the script in which it's defined.
Environment variables only affect the msys process and any child processes started from that shell. If you want it to persist after you close the command line and start a new one, you will need to put it into a script such as .bashrc
Related
Some operations related to embedded Linux (e.g. Kernel build etc) requires the use of toolchain, thus the first command is:
$ source /opt/fslc-x11/2.2.1/environment-setup-armv7at2hf-neon-fslc-linux-gnueabi
I'd like to place this command inside a .sh script for Ubuntu: what's the right way?
I installed Haskell on my MacOS system using ghcup installer. It worked because if I type ghci I am dropped into this interactive shell. However I got this message in the terminal after doing the install:
In order to run ghc and cabal, you need to adjust your PATH variable.
You may want to source '/Users/user1/.ghcup/env' in your shell
configuration to do so (e.g. ~/.bashrc).
Detected bash shell on your system...
If you want ghcup to automatically add the required PATH variable to "/Users/user1/.bashrc"
answer with YES, otherwise with NO and press ENTER.
YES
grep: /Users/user1/.bashrc: No such file or directory
My shell is bash 3.2 But as you can see, when I typed YES it says there is no such file. How do I find my shell configuration file, or resolve this? I'd like to complete the setup correctly here.
And I have to be honest about my level of knowledge here, I don't truly understand what this is asking exactly. Is the PATH variable 'env'?
On macOS, .bashrc does not exist by default. ghcup will create this file, so the command you ran will have worked correctly. However, one of ghcup's subcommands expected to find the file before it was created, and therefore reported that error message. You can safely ignore this.
I have made a few python scripts, but is there an easier way to run them? I am using cygwin.
python "C:\Users\Desk\Dropbox\scripts\wsort.py" > data11414_unsorted.txt < data11414_sorted.txt
I want something like this (not typing the path name or "python"):
wsort > data11414_unsorted.txt < data11414_sorted.txt
where wsort is a link to my real wsort.py
Add a
Shebang
to the script
#!/bin/python
then invoke like this
wsort.py > data11414_unsorted.txt < data11414_sorted.txt
First, your question has a Windows-style path (backslashes, beginning with C:) rather than a Cygwin path (/cygdrive/c/Users/Desk/Dropbox/scripts/wsort.py). That implies you're not actually using Cygwin, or if you are, you're ignoring a bunch of warnings.
The below assumes you're using Cygwin Bash (which should be what you get if you start Cygwin Terminal from the Start Menu) and Cygwin Python (which you've installed using Cygwin's setup.exe, not a Windows Python installer). If your not, you're making life more difficult for yourself than you need to.
That out the way, there's a bunch of steps you need to take:
First, make the script executable. Use the chmod command for that, from a Cygwin Bash shell:
chmod +x /cygdrive/c/Users/Desk/Dropbox/scripts/wsort.py
Second, tell the system how to execute it. Add the following line to the top of the script:
#!/bin/python
(That's a "shebang". Python sees it as a comment, so doesn't do anything with it, but Cygwin and other Linux-like systems will use that line to see which program to run the script with. In this case, Python.)
Third, make sure your line endings are correct. Cygwin expects Linux line endings and will fail without them. This may not be a problem, but there's no harm in doing this. Run the following command:
dos2unix /cygdrive/c/Users/Desk/Dropbox/scripts/wsort.py
At this point, you'll be able to call the script by specifying the full path to it in Cygwin. You can't yet run it without specifying where the script is explicitly.
The fourth step is making sure the script is "in your path", ie in one of the folders where Cygwin looks for scripts to run. There are lots of ways to do this, but the most sensible is probably to just add your scripts directory to your path. The following command will add your scripts directory to your path whenever you start a new Cygwin session:
echo 'PATH="/cygdrive/c/Users/Desk/Dropbox/scripts:$PATH"' >>~/.bashrc
You will need to restart your Cygwin terminal for that to take effect, however.
At that point, you'll be able to run the script in Cygwin just by typing wsort.py (and thus use it with redirections and so forth as in your question).
Finally, to be able to call it simply as wsort, there's a number of options. The obvious one is just renaming the file. More usefully (and without copying the file or doing anything liable to break with Dropbox syncing things), try creating an alias:
echo 'alias wsort=wsort.py' >>~/.bashrc
Again, you'll need to restart your Cygwin terminal for that to take effect.
Maybe use an alias ?
alias wsort = "Command_Used"
I have been trying to setup a environment variable in Cygwin using the command export PRIMOSBASE=/directory/for/primosfiles.
And when i check the variable using the command echo $PRIMOSBASE it shows the /directory/for/primosfiles. hopeful this means the environment variable is set.
But when i try to run a shell script(primos) for the /directory/for/primosfiles, it shows
./primos: line 8: /prilaunch.pl: No such file or directory
chmod: failed to get attributes of `step1.sh': No such file or directory
which means i have not set the PRIMOSBASE environment. could anyone please tell me where i am going wrong...
Thanks ...
Run
echo "export PRIMOSBASE=/directory/for/primosfiles" >> ~/.bashrc
to append the command to the end of your .bashrc file, so that the variable is set each time you use Cygwin. Then run
source ~/.bashrc
to make it take effect immediately.
NOTE: Make sure you use double brackets (>>) to append. It might be a good idea to make a backup of .bashrc just in case. If you're not comfortable with I/O redirection, an alternative is to edit .bashrc with an editor. I think vim is among the default tools in Cygwin.
I had a similar issue trying to get ANDROID_HOME to work in a Cygwin window. When I used the linux path separators, as follows
ANDROID_HOME=/cygdrive/c/Users/User/AppData/Local/Android/sdk my gradlew build script complained it couldn't find the sdk in ANDROID_HOME.
I eventually discovered that I had to set my environment variable in the Windows format, including Windows path separators '\', as follows
ANDROID_HOME=C:\Users\User\AppData\Local\Android\sdk
Note: the PATH and several other environment variables set in Windows are converted into Linux format. I hope this helps others who want/need to use Cygwin + Windows + essentially Windows programs that need environment variables.
I have recently started using cython and now want to use the -a tag as shown http://docs.cython.org/src/quickstart/cythonize.html#determining-where-to-add-types to see how my code is doing. However to use this I need to access the cython command line program. My question is how to do this. I am running windows and tried adding C:\Python32\Lib\site-packages\Cython to my path environmental variable and the typing cython on command line, but this didn't work. Thank you for your time
Scripts and executables are stored in the Scripts/ directory in the python install directory. In my case, I installed python3 in C:\Python31, so I added C:\Python31\Scripts to my path. This allows me to use cython on the command line.
Note that I have to type "cython.py" and not "cython" on the command line, since the Scripts/ directory contains a "cython.py" file, and not a "cython" file.
If you just want the -a (annotation) HTML file, you do NOT necessarily need to use the command line. See https://stackoverflow.com/a/11075375/1272672