bash function: md.view

One of my favorite bash functions is md.view, which is available in my dotfiles repository.

# test markdown files, probably a better way to test for programs.
function md.view {
    local i=true
    type -p markdown &> /dev/null || i=false
    if $i ; then 
        local output="/tmp/md.view-$(date +%F).html";
        markdown $1 > "$output";
        google-chrome "$output"; # xdg-open would open default browser after next line executes
        rm "$output";
    else
        echo "markdown is not installed"
    fi
}

There's not really anything particularly cool about this function. It checks for markdown and reminds me to install it if I haven't yet. It doesn't do this for Google Chrome because that's the first application I install on new machines. Usually, you'd use xdg-open to choose a browser, but this can cause problems with the remove command at the end of the function (depending on how the browser creates its process).

Anyway, this is really useful when I'm creating README files using markdown for my github repositories. For instance, I was just updating a README to refer to *_32.png images. The problem is that * and _ are special tokens in markdown. I'd never attempted to escape one after the other, which is often broken in parsers. With this function in my extended .bash\functions, I can quickly check output with:

$ md.view README.md

I know, it's such a simple thing to have as a favorite. Sometimes really simple things have a huge impact, especially if you type out README files regularly

Linux tip: Alias ‘cd’ in bash shell

A while ago, I stumbled across an excellent article at O'Reilly with tips for your bash shell.

I wanted to expand on the "pushd/popd" section a little.

First, check your ~/.bashrc file for the following lines:

if [ -f ~/.bash_aliases ]; then
    . ~/.bash_aliases
fi

This checks that the ~/.bash_aliases file exists, and if it does, it loads it using the '.' builtin. If you aren't familiar with the source/. builtin, here is an excerpt from the documentation:

. (a period)
. filename [arguments]

Read and execute commands from the filename argument in the current shell context. If filename does not contain a slash, the PATH variable is used to find filename. When Bash is not in posix mode, the current directory is searched if filename is not found in $PATH. If any arguments are supplied, they become the positional parameters when filename is executed. Otherwise the positional parameters are unchanged. The return status is the exit status of the last command executed, or zero if no commands are executed. If filename is not found, or cannot be read, the return status is non-zero. This builtin is equivalent to source.

Now, create or edit ~/.bash_aliases with the following content:

alias cd="pushd"
alias bd="popd"
alias cd..="cd .."
alias cd...="cd ../.."
alias cd....="cd ../.."
alias cd.....="cd ../../.."
alias cd......="cd ../../../.."

This aliases cd to push the result onto the directory stack (pushd). Then, we introduce a bd command to pop the last directory off the stack (popd).

If you're like me, you get tired of typing cd ../../../.., which is still faster than typing cd /home/jim/projects/al [TAB]/src or something similar. So, the last lines alias quite a few levels of directory changes so you type cd.. followed by the number of directories you want to navigate back.

Here are some examples:

jim@schubert:~$ cd projects/newtabredirect/
~/projects/newtabredirect ~

jim@schubert:~/projects/newtabredirect$ cd ~/projects/select-actions/
~/projects/select-actions ~/projects/newtabredirect ~

jim@schubert:~/projects/select-actions$ cd ~/Documents/blogs/
~/Documents/blogs ~/projects/select-actions ~/projects/newtabredirect ~

jim@schubert:~/Documents/blogs$ bd
~/projects/select-actions ~/projects/newtabredirect ~

jim@schubert:~/projects/select-actions$ cd....
~ ~/projects/select-actions ~/projects/newtabredirect ~

jim@schubert:~$ pwd
/home/jim