How to Fgrep 2 Dashes '-'

How can I grep for a string that contains multiple consecutive dashes?

With -+ you are saying: multiple -. But this is not understood automatically by grep. You need to tell it that + has a special meaning.

You can do it by using an extended regex -E:

grep -E -- "-+" file

or by escaping the +:

grep -- "-\+" file

Test

$ cat a
---0 [58ms, 100%, 100%] 
hell
$ grep -E -- "-+" a
---0 [58ms, 100%, 100%] 
$ grep -- "-\+" a
---0 [58ms, 100%, 100%]

From man grep:

REGULAR EXPRESSIONS

Basic vs Extended Regular Expressions

In basic regular expressions the meta-characters ?, +, {, |,
(, and ) lose their special meaning; instead use the backslashed
versions \?, \+, \{, \|, $, and $.

How can I grep for a string that begins with a dash/hyphen?

Use:

grep -- -X

Documentation

Related: What does a bare double dash mean? (thanks to nutty about natty).

grep regex solution for finding 3 or more dashes in a string

this will print all directory names with 3 or more dashes

find . -type d -exec sh -c '[ $(echo {} | grep -o - | wc -l) -ge 3 ]' \; -print

How to extract text between first 2 dashes in the string using sed or grep in shell

You can use awk keeping in mind that in Makefile the $ char in awk command must be doubled:

url=$(shell echo 'feature/test-111-test-test' | awk -F'-' '{gsub(/\//, "-", $$1);print $$1"-"$$2"-"}')
echo "$url"
# => feature-test-111-

See the online demo. Here, -F'-' sets the field delimiter as -, gsub(/\//, "-", $1) replaces / with - in Field 1 and print $1"-"$2"-" prints the value of --separated Field 1 and 2.

Or, with a regex as a field delimiter:

url=$(shell echo 'feature/test-111-test-test' | awk -F'[-/]' '{print $$1"-"$$2"-"$$3"-"}')
echo "$url"
# => feature-test-111-

The -F'[-/]' option sets the field separator to - and /.

The '{print $1"-"$2"-"$3"-"}' part prints the first, second and third value with a separating hyphen.

See the online demo.

Make grep search patterns starting with dash

Just use \\-f

$ ls --help | grep \\-f
  -f                         do not sort, enable -aU, disable -ls --color
      --file-type            likewise, except do not append '*'
      --format=WORD          across -x, commas -m, horizontal -x, long -l,
      --full-time            like -l --time-style=full-iso
      --group-directories-first
                               file-type (--file-type), classify (-F)

Regex for line containing one or more spaces or dashes

Something like that should work:

grep -E -- ' |\-' file.txt

Explanation:

-E: to interpret patterns as extended regular expressions
--: to signify the end of command options
' |\-': the line contains either a space or a dash

How to grep for two words existing on the same line?

Why do you pass -c? That will just show the number of matches. Similarly, there is no reason to use -r. I suggest you read man grep.

To grep for 2 words existing on the same line, simply do:

grep "word1" FILE | grep "word2"

grep "word1" FILE will print all lines that have word1 in them from FILE, and then grep "word2" will print the lines that have word2 in them. Hence, if you combine these using a pipe, it will show lines containing both word1 and word2.

If you just want a count of how many lines had the 2 words on the same line, do:

grep "word1" FILE | grep -c "word2"

Also, to address your question why does it get stuck : in grep -c "word1", you did not specify a file. Therefore, grep expects input from stdin, which is why it seems to hang. You can press Ctrl+D to send an EOF (end-of-file) so that it quits.