bash: syntax error near unexpected token `foo'

Question

I have a command I am trying to alias for simplicity:

php artisan route:list | (head -n 3; grep checkout)

This command shows me the header of this table and searches for the route. The result looks like this:

+--------+----------+--------------------------------------------+----------------------------------------------------+-------------------------------------------------------------------------------+------------------------------------------------------+
| Domain | Method   | URI                                        | Name                                               | Action                                                                        | Middleware                                           |
+--------+----------+---------------------------------------------+----------------------------------------------------+-------------------------------------------------------------------------------+------------------------------------------------------+
|        | POST     | profile/auctions/checkout                  | user-portal-profile-auctions-checkout              | xxxxxxxxxxxxxxxx                   | web,auth                                             |
|        | POST     | profile/deals/checkout                     | user-portal-profile-deals-checkout                 | xxxxxxxxxxxxxx                     | web,auth                                             |
|        | POST     | profile/quotes/checkout                    | user-portal-profile-quotes-checkout                | xxxxxxxxxxxxxxx                    | web,auth                                             |

So this is what I have in my ~/.bash_profile:

alias findRoute='php artisan route:list | (head -n 3; grep $1)'

But I keep getting this error:

bash: syntax error near unexpected token `checkout'

What gives? Why will it not accept my argument?

I have tried using single and double quotes in the argument I pass.

I have tried using single and double quotes in the alias. Nothing changes.

Answer 1

Alias expansion is just text replacement followed by another round of parsing by the shell.

When you enter

findRoute checkout

That's first expanded to:

php artisan route:list | (head -n 3; grep $1) checkout

And that result is again parsed as shell code. That's invalid shell code here.

You'd want to use a script or function instead here. Like:

findRoute() {
  php artisan route:list | {
    head -n 3
    grep -e "$1"
  }
}

Now, beware that head may read more than 3 lines, even though it outputs only 3 as most head implementations read by entire blocks. That means grep would not get to see that part.

If your sed is the GNU implementation, you can replace head -n3 with sed -u 3q, where sed reads the input one byte at a time so as not read past the third newline characters.

Alternatively, you could use awk instead as:

findRoute() {
  php artisan route:list |
    PATTERN=$1 awk 'NR <= 3 || $0 ~ ENVIRON["PATTERN"]'
}

Beware $1 is then interpreted as an extended regular expression (like for grep -E) instead of a basic one (with grep without -E). For a substring search (as in grep -F), replace with:

findRoute() {
  php artisan route:list |
    PATTERN=$1 awk 'NR <= 3 || index($0, ENVIRON["PATTERN"])'
}