Category: Programming Language

In Bash—Pass Arguments From Function To Another

When I’m good about using and re-using functions in Bash I always end up passing arguments through from one function to another. For example: 

function pie {
  open /Applications/Emacs.app --args --debug-init "$@"
}

function pienthm {
  EMACSNOTHEME=t pie --reverse-video "$@"
}

Horrible to admit but I keep forgetting the syntax even are taking copious notes on the GNU Bash manual.

BTW: hear, hear to including Bash-isms in every shell script!

Find All Locations Of A Binary Using `type’ not `which’

I can’t find the git 2.10 binary so I run

which git

/usr/local/bin/git

Excellent, found it.

And then I check it’s version to verify I am looking at the right version

/usr/local/bin/git –version

git version 2.21.0

Oops that isn’t what I wanted.

There must be another git getting loaded earlier in the search path.

Here is how to find out where all copies of git live

type -a git

git is /usr/local/bin/git
git is /usr/local/bin/git
git is /usr/bin/git

Look for the right git at version 2.10

/usr/local/bin/git –version
/usr/bin/git –version

git version 2.21.0
git version 2.14.3 (Apple Git-98)

I want the second one.

That is how to track down the location of a binary file on macOS that appears multiple times in the search path.

Avoid Most Bash Errors Pretty Much By Quoting Everything, And More Best Practices

This page shows common errors that Bash programmers make. These examples are all flawed in some way.

You will save yourself from many of these pitfalls if you simply always use quotes and never use WordSplitting for any reason! Word splitting is a broken legacy misfeature inherited from the Bourne shell that’s stuck on by default if you don’t quote expansions. The vast majority of pitfalls are in some way related to unquoted expansions, and the ensuing word splitting and globbing that result.

All of us have fallen into one of these pits.

Why not use Python instead? 🙂

Oh yea, non-interactive shells 😠.

More on Quotes and Word Splitting.

Fix For When Bash Can’t Find Its Debugger On macOS

Sometimes Bash needs its debugger but it can’t find it. It looks like this: 

/usr/share/bashdb/bashdb-main.inc: No such file or directory
-bash: warning: cannot start debugger

For example when you start bashdb yourself with bash --debugger or set shopt -s extdebug. Another example is when your terminal turns it on.

Here is the fix that worked on my box:

brew install bashdb
bashhome=$(brew –prefix bash)
bdbhome=$(brew –prefix bashdb)
ln -s $bdbhome/share/bashdb $bashhome/share/bashdb
unset bashhome
unset bdbhome