newspaint

Documenting Problems That Were Difficult To Find The Answer To

Monthly Archives: January 2017

Rust/Cargo Outputting Dollar Angle Bracket Symbols

So you’re compiling source using Cargo/Rust and you see output similar to the following:

error[E0046]$<2>: not all trait items implemented, missing: `decode`, `encode`$<2>
  $<2>--> $<2>src/main.rs:7:1$<2>
   $<2>|$<2>
7$<2>  $<2>| $<2>impl tokio_core::io::Codec for LineCodec {$<2>
   $<2>| $<2>^$<2> missing `decode`, `encode` in implementation$<2>

error$: aborting due to previous error$

This is full of dollar, angle bracket, number, angle bracket characters.

The fix is to change your terminal, e.g.:

TERM=xterm

On doing this I had the output in full colour without the mysterious symbols.

Conditionally adding a directory to PATH if not already in PATH

In BASH it is possible to check that a directory is not already in the PATH environment variable before adding it.

The basic string-in-string search function was adopted from this forum post.

stringContains() { [ -z "${1##*$2*}" ]; }
stringBegins()   { [ -z "${1##$2*}"  ]; }
stringEnds()     { [ -z "${1##*$2}"  ]; }

# call as inPath "$PATH" "/my/new/path"
inPath() {
  if stringBegins   "$1" "$2:";  then return 0; fi
  if stringEnds     "$1" ":$2";  then return 0; fi
  if stringContains "$1" ":$2:"; then return 0; fi
  if [ "$1" == "$2" ];           then return 0; fi
  return 1;
}

If you wanted to, say, add “/home/myuser/bin” if it didn’t already exist, you could add the above functions and the following:

if inPath "$PATH" "/home/myuser/bin"; then
  : # do nothing
else
  PATH="$PATH:/home/myuser/bin"
fi