gcc -v --help 2> /dev/null | sed -n '/^ *-std=\([^<][^ ]\+\).*/ {s//\1/p}'
  

Note you can tag on a | grep c++ or | grep c to get the standards supported by a particular langauge

Explanation

Step 1: gcc -v --help 2> /dev/null

• gcc -v --help prints a lot of information about GCC, including available command-line options.
• 2> /dev/null redirects stderr to /dev/null. GCC prints help options to stderr, so this suppresses messages you don’t care about.

Step 2: | sed -n '...'

• The pipe (|) sends GCC’s output to sed.
• sed -n disables the default printing behavior. Normally, sed prints every line after processing; -n tells it to print only when explicitly using p.

Step 3: The sed script

/^ *-std=\([^<][^ ]\+\).*/ { s//\1/p }

a) Pattern match: ^ *-std=\([^<][^ ]\+\).*

• ^ * → matches the start of the line followed by zero or more spaces.
• -std= → literally matches -std=.
• \([^<][^ ]\+\) → a capturing group:
  • [^<] → matches any character except <.
  • [^ ]\+ → matches one or more characters that are not a space.
• .* → matches the rest of the line (any characters, zero or more).

This pattern looks for lines like:

  -std=c++17
-std=c++20

It avoids matches like -std=<something>.

b) Action block: { s//\1/p }

• s//\1/ → substitute the matched pattern with the first capture group \1.
• p → print the result.

Effectively, it takes a line like:

  -std=c++17

and outputs:

c++17

Summary

• The command extracts all -std= compiler versions that GCC supports.
• It ignores entries starting with <.
• Outputs just the version strings like:

c++98
c++03
c++11
c++14
c++17
c++20
c++23