When I wrote the code to automatically generate aliases for hosts in my SSH config I started thinking about how checks are never done to verify we are not overriding an existing alias. This is my solution for it. I almost think that alias should be an alias for register_alias so that all aliases get checked, but I’m sure there could be an instance where it would break something. Let me know what you think about assigning aliases this way.

# .bash_functions
function register_alias() {
  local alias=$(echo $* | cut -d'=' -f 1)
  local TEMP_CMD=$(which $alias)
  local TEMP_ALIAS=$(echo "`alias`" | sed 's/alias\ \(.*\)=.*/\1/' | grep ^$alias$)
  if [ ${#TEMP_CMD} -gt 0 ]; then
    echo "Alias $alias conflicts with command $TEMP_CMD"
  elif [ ${#TEMP_ALIAS} -gt 0 ]; then
    echo "Alias $alias conflicts with alias $alias"
  else
    alias "$*"
  fi
}

# .bashrc
if [ -f ~/.bash_functions ]; then
  . ~/.bash_functions
fi

# .bash_aliases

register_alias sls='screen -ls'
register_alias sdr='screen -d -r'

Update: I changed the TEMP_ALIAS line to use sed instead of cut/sed

There are some aliases and small scripts I use on a normal basis.

I prefer to just type in the machine I want to ssh to instead of typing ssh in front of it. This chunk of code goes in my ~/.bashrc file and creates an alias for each “Host …” entry in ~/.ssh/config. It checks to see if there is an existing command that matches the Host entry, and alerts you if there is a conflict

# Generate SSH aliases
for host in $(grep ^Host .ssh/config | sed s/Host\ //g); do
  TEMP_CMD=$(which $host)
  TEMP_ALIASES=$(echo "`alias`" | sed 's/alias\ \(.*\)=.*/\1/' | grep ^$host$)
  if [ ${#TEMP_CMD} -gt 0 ]; then
    echo "Alias $host conflicts with command $TEMP_CMD"
  elif [ ${#TEMP_ALIASES} -gt 0 ]; then
    echo "Alias $host conflicts with alias $host"
  else
    alias $host="ssh $host"
  fi
done

When you open a terminal you will see something like this if you have conflicts.

Alias www conflicts with alias www
Alias hg conflicts with command /usr/bin/hg
Alias git conflicts with command /usr/bin/git
[20:05:21] manis@baron:~$

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