How to match everything from after the last YAML delimiter onwards

Question

I normally use grep to search for a pattern in a string. However in this particular instance I have to identify a YAML header, also, it ends with a triple dash.

My test.info file has the following content

---
title: dont't know
draft: true
---
this is a test to add some extra content

I want the following output, i.e. everything from after the last YAML delimiter until the end of the file:

this is a test to add some extra content

When I enter the dashes, bash return the following error:

$ cat test.info | grep '---' -A1
grep: unrecognized option `---'

I tried to “escape” the dashes unsuccessfully. Any idea? This is for BSD grep. The things that get me confused is that I can get what I want if I do something like the following.

$ cat test.info | grep 'this' -A1

Problem is that I don't know what's the first word.

I can grep the file as recommended, but the tool returns the pattern and not everything immediately after:

$ grep -m 1 -e '---' test.info 
---
$ grep -- --- test.info | tail -1
---

Answer 1

So, without taking any credit as I don't want, I just post the solution that worked on my mac thanks to KasiyA

tail -r file| awk '/---/ {exit} {print}'| tail -r

Answer 2

How about this command?

tac file| awk '/---/ {exit} {print}'|tac

On OSX just replace both tac commands with tail -r

From man tac:

 tac - concatenate and print files in reverse - reverse of cat command ;)

Output of tac file:

next line
this is a test to add some extra content
---
draft: true
title: dont't know
---

The awk command awk '/---/ {exit} {print}' prints all lines until first matched pattern found.

Output:

next line
this is a test to add some extra content

then run tac command again to reverse to default.

Output:

this is a test to add some extra content
next line

Answer 3

$ line=$(grep -n -- --- test.info | tail -n 1 | cut -d: -f1);tail -n +$(( $line + 1 )) test.info 
this is a test to add some extra content

Appropriate error checking needs to be added, as in if $line 'not numeric' ...

The original problem comes from the fact that you need to escape - or tell the program that it is not an option:

$ grep -n -- --- test.info
1:---
4:---

Most(?) gnu software has "--" as an option; telling to stop parsing for more options after that point.

Note:
$ grep --version
should tell if it is a GNU grep utility or not.

$ grep -h
or
$ grep --help
usually tells the options it understands.

Answer 4

Using awk:

awk 'END{print}' RS='---' file

RS defines --- as record separator and with END{print} we only prints the last record.

Using sed:

sed -r ':a;$!{N;ba};s:^(.*\n?)---::' file

Answer 5

I see at least two different ways to do it. In fact you need to escape the first "-"

Using option -e:

grep -e "---" test.info

Escaping the first "-" with backslash:

grep "\---" test.info

Answer 6

Addressing one aspect of your (now original) question.

(And your new questions stills talks about grep and -A1 and pretends that you can't find a way to specify 3 hiphens and that's just wrong because in your comments you've shown that you can).

[your original question asked how to show results FROM a point. when actually you want FROM AFTER. Your new question still stated 'from' I updated it to 'from after' ]

If does look like grep and -A1 aren't what you want though it's still mentioned even in your updated question

I don't see any funny results. Perhaps you can paste the results you think are funny. [you now have]

If you do grep pattern -A1 then it dumps the pattern followed by the next line. And it dumps -- after each match.

e.g.

$ cat t3.info
,,,
qwerty
uiop
,,,




werwer
werwer
,,,,,
werwerwer
werwerwer
werwerwer
,,,,



$ cat t3.info | grep -P ',,,' -A1
,,,
qwerty
--
,,,

--
,,,,,
werwerwer
--
,,,,



$

You could do grep -P '(?=---)...' -A1 Another thing you can try is this grep -P '\x2d{3}' -A1

And if your file has ---

$ cat t3.info
---
qwerty
uiop
---




werwer
werwer
---
werwerwer
werwerwer
werwerwer
---

Sure this doesn't work

$ cat t3.info | grep -P '---' -A1 grep: unrecognized option '---' Usage: grep [OPTION]... PATTERN [FILE]... Try 'grep --help' for more information.

But this works

$ cat t3.info | grep -P '\---' -A1
---
qwerty
--
---

--
---
werwerwer
--
---

and this works

$ cat t3.info | grep -P '(?=\x2d{3})...' -A1
---
qwerty
--
---

--
---
werwerwer
--
---

grep version 2.16

$ grep --version
grep (GNU grep) 2.16

If you don't want to be including your pattern then whatever option you use it wouldn't be -A1 and I don't see why you are having trouble with matching ---

It may be that to do what you want with grep or something grep like, you need to match new line e.g. e.g. regex of positive lookbehind.. for ---\n but apparently grep can't match new lines, in which case you might have more luck with pcregrep https://stackoverflow.com/questions/2686147/how-to-find-patterns-across-multiple-lines-using-grep or some other way. S oyour question is more, how can you match what follows on the line after a pattern.