macOS sed replace content and write it to file

 find . -name '*.php' | xargs -I{} sed -i ''  's/strA/strB/' {}

find

If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information.  

sed

-n, --quiet, --silent

suppress automatic printing of pattern space

--debug

annotate program execution

-e script, --expression=script

add the script to the commands to be executed

-f script-file, --file=script-file

add the contents of script-file to the commands to be executed

--follow-symlinks

follow symlinks when processing in place

-i[SUFFIX], --in-place[=SUFFIX]

edit files in place (makes backup if SUFFIX supplied)

-l N, --line-length=N

specify the desired line-wrap length for the `l' command

--posix

disable all GNU extensions.

-E, -r, --regexp-extended

use extended regular expressions in the script (for portability use POSIX -E).

-s, --separate

consider files as separate rather than as a single, continuous long stream.

--sandbox

operate in sandbox mode (disable e/r/w commands).

-u, --unbuffered

load minimal amounts of data from the input files and flush the output buffers more often

-z, --null-data

separate lines by NUL characters

--help

display this help and exit

--version

output version information and exit

If no -e, --expression, -f, or --file option is given, then the first non-option argument is taken as the sed script to interpret. All remaining arguments are names of input files; if no input files are specified, then the standard input is read.

GNU sed home page: <https://www.gnu.org/software/sed/>. General help using GNU software: <https://www.gnu.org/gethelp/>. E-mail bug reports to: <[email protected]>.