mjhjmtu

I want to make function that parses from text pasted in a terminal.

$ cat <<eof | grep --color sometext
> foo
> sometext
> sometext1
> a sometext
> asdf
> 
> eof
sometext
sometext1
a sometext

While the above works I can make neither an alias nor a function of it.

alias gsi='cat <<eof | grep --color "$1"'
gsi cat <<eof 

I thought redirections weren't executed during function definition.

alias 'gsi=<<eof grep --color'

Would work as alias is just like preprocessor text replacement, where the replacement is interpreted as shell code again.

Yours was not working as you had that "$1". With gsi file.txt replaced with cat <<eof | grep --color "$1" file.txt, then the shell carries on interpreting that command line and $1 at that point is the shell's first positional parameter which is probably empty unless you did a set something beforehand. So you'd want to remove that "$1" here. You can remove the UUOC as well.

gsi() cat <<eof 

is wrong from a syntax point of view as the eof line is missing after that cat <<eof.

Your function would not be using a here-document:

gsi () 
 grep --color "$@"

This would enable you to pass a pattern as well as any other options to grep on the common line and grep would read from standard input.

The end of the input would be signalled by pressing Ctrl+D.

The above would possibly intermingle the pasted contents and the result from grep. To accumulate the pasted content first and then run grep, you could use something like

gsi () 
 trap 'rm -f "$buffer"' RETURN
 local buffer="$(mktemp)"
 cat >"$buffer" && grep --color "$@" "$buffer"

Here, the pasted output is put into a temporary file before the grep is run. The temporary file is removed when the function exits. This is approximately what bash would do behind the scenes when you paste into a here-document.

You mentioned you're pasting to terminal. Abandon here-doc altogether, and use a proper clipboard utility, such as xclip (or pbpaste on Mac OS X). With xclip that'd be done as

xclip -o -sel clip | grep --color 'sometext'

See also 'xclip' vs. 'xsel' on the difference between the two utilities.