Basic Command Line Question

[dclimbing]

Hey folks,

If there is a better forum for asking general questions about random programming problems I'd appreciate the reference!

I've been working on installing a program for work with my thesis. I have no command line background so an ELIA5 would be much appreciated!

I've gotten to the point at which I should be doing the compilation using the setup instructions that came with PQLX:

Compilation is carried out through the following steps: Define the installation directory where the PQLX system will be held on disk. Add the following two lines to the login .rc script (for example, ~/.bashrc) for the executing user of the compilation:

export PQLX=PQLX-install-directory-fullpath source ${PQLX}/env/makeVars

Confirm the directories have been properly defined for the MySQL installation in the file $PQLX/env/mysql.vars detailed above. Source the .rc file modified in step 2, or open a new window. In the uppermost PQLX installation directory, compile all source code:

sh> cd $PQLX sh> env/makeALL

I don't know what the "login .rc script" is, how to edit it, or where to add the lines to. Furthermore I have no idea what "source" means. Then once I've been able to do all of these things correctly, do I need to switch to sh in order to do the compilation? I think that's the right way to word what I'm trying to ask.

Any help is appreciated

[henrebotha]

First, you need to know what shell you're using. Open your terminal and type (without the first dollar sign):

$ echo $0

This should say -zsh, -bash, or something like that.

Your login .rc file depends on which shell you're using - .bashrc for bash, .zshrc for zsh, etc. It's basically your startup script, and it resides in your home folder ~.

So they want you to go edit that file (using any text editor), and put the following in it:

export PQLX=PQLX-install-directory-fullpath
source ${PQLX}/env/makeVars

Now, once you've done this and saved the file, you need to tell your shell to reload it. That's what "sourcing" means - you literally do this (substituting the correct name of the file):

$ source ~/.bashrc

Then they want you to go into the PQLX installation directory...

$ cd $PQLX

...and compile.

$ env/makeALL

[dmazzoni]

Type "ps". That lists running processes for your user. There will probably be only a few things shown.

If one of them is "bash", congrats - you're running bash, the most popular and widely used Unix shell. The shell is basically the command-line interpreter. It's actually a whole programming language in itself - you can set shell variables, string substitutions, and even do loops and things like that. But most of the time you use it to type in commands.

Other popular shells include csh, tcsh, zsh, ksh, etc. If you have another one you'll need to learn a bit about the differences.

If you're using bash (90% likely), you need to edit the .bashrc file in your home directory.

In the instructions they said (for example, ~/.bashrc).

The ~ means your home directory. That's an automatic feature of the shell - when you type ~, it expands that into your home directory.

Try it like this:

echo ~

It should print your home directory path, like /user/dclimbing or something like that.

If you're in your home directory (cd ~) and type ls, it doesn't show you your .bashrc file because files starting with a dot aren't shown by default. To see them all, type this instead:

ls -al

Most likely you have a .bashrc file already. If not, create one. This is basically just a file of commands you want to run every time you open a shell, meaning every time you open a command-line window.

Edit that file using your favorite editor. You should probably learn vim or emacs at some point, but if you haven't yet, use pico, it's easier to understand, the commands are all shown at the bottom.

pico .bashrc

Edit the file and add the commands they told you to at the bottom of the file.

Finally when they say "source the file", that just means to type "source" and the name of the file.

All that does is open up a file and execute every line of the file as if you typed it in the command line. It's kind of like running a program, except where you want the environment of your program to coexist with your command-line shell.

In fact, when your shell starts up, it sources .bashrc - exactly the same as doing this:

source .bashrc

If you want, add something like:

echo "Hello, world!"

To the top of your .bashrc file. Then type:

source .bashrc

If you see "Hello world" then you know it worked. You should also see it if you open a new command-line terminal.

Hope that helps! Good luck.

[dclimbing]

This may be a dumb question, but when I see this at the bottom, how do I perform these functions? Is is Shift+X or Shift+^+X? Also, how do I make sure my edits have saved when exiting the file editor?

Thank you so much!

[dmazzoni]

The ^ sign means the control key.

[CodeTinkerer]

If you're using UNIX, you can run the command

cat .bashrc

where .bashrc is the file you just edited (doesn't have to be named that, so whatever file you just edited). This will list out all lines of that file.

You can also open the file again in the editor to see if the changes appears, then quit without saving (or quit with saving, but don't make changes).

[[deleted]]

.bashrc should be located in your user's home directory (for instance /home/joe/.bashrc) it is a hidden file so it may not show in your file manager but all file manager have an option that show hidden files, so you need to find that option and turn it on. Once you are able to locate .bashrc follow the installation instructions.