I'm trying to create an alias that starts with a pipe.
ex:
echo -i "hello\nworld" | grep world
> world
alias gr="| grep"
echo -i "hello\nworld" gr world
> hello
> world gr world
I.e, if the alias start with a pipe, aliasing doesn't seem to work properly. Is there a way to do this?
From man bash:
Aliases allow a string to be substituted for a word when it is used as the first word of a simple command.
Pipe can't be the first word of a simple command.
eval to execute a dynamically constructed command line).
gp expands to | grep -i cheatsheet
Commented
Jan 20, 2019 at 11:53
Oh, your alias works. Try gr alone and your shell will throw syntax error because of | at the beginning of the line. That clearly means the alias works, i.e. it substitutes one string for another when it is supposed to.
In your example gr is treated as an argument to echo, that's why there is no substitution. It wouldn't be, even if there was no pipe inside the alias. The initial pipe symbol doesn't decide whether aliasing occurs or not; however it leads to an error when it does but this error has nothing to do with alias mechanics.
If you can/want to switch shell, you can do this in zsh, by setting the alias as
alias -g gr="| grep"
zshwith a "global alias" but get to keep all the pieces when things break.