git grep and OR'd multiple clauses with pipe? - linux

Question

I want to search for multiple clauses with grep - and I know that one can use a pipe | to OR the clauses; so here is a test I'm trying on MSYS2, Windows 10:
$ uname -s
MSYS_NT-10.0-18363
$ git --version
git version 2.25.2
$ grep --version | head -1
grep (GNU grep) 3.0
$ git clone https://github.com/xythobuz/avrSerial.git
...
$ cd avrSerial/
$ grep -r 'SERIALDATA\|UART_INTERRUPT_MASK' . --include='*.[ch]'
./serial.c:#define SERIALDATA 0
./serial.c: rxBuffer[uart][rxWrite[uart]] = *serialRegisters[uart][SERIALDATA];
./serial.c: *serialRegisters[uart][SERIALDATA] = sendThisNext[uart];
./serial.c: *serialRegisters[uart][SERIALDATA] = txBuffer[uart][txRead[uart]];
./serial.c: serialRegisters[uart]->CTRLA &= ~(UART_INTERRUPT_MASK << 2); // TXCINTLVL
./serial_device.h:#define UART_INTERRUPT_MASK 0x03
So, just grep works fine here, with multiple clauses with pipe.
However, I'd like to know in which C functions do the clauses/keyword matches occur, so I try to use git grep with the -p switch:
$ git grep -p 'SERIALDATA\|UART_INTERRUPT_MASK' -- '*.[ch]'
$
... and absolutely nothing is returned, for the same clause.
However, if I repeat this test on Ubuntu:
$ echo `uname -s` `cat /etc/issue | head -1`
Linux Ubuntu 18.04.4 LTS \n \l
$ git --version
git version 2.17.1
$ grep --version | head -1
grep (GNU grep) 3.1
# same procedure with git clone, cd ... grep -r works the same too; but git grep -p is different:
$ git grep -p 'SERIALDATA\|UART_INTERRUPT_MASK' -- '*.[ch]'
serial.c:#define SERIALDATA 0
serial.c=static void serialReceiveInterrupt(uint8_t uart) {
serial.c: rxBuffer[uart][rxWrite[uart]] = *serialRegisters[uart][SERIALDATA];
serial.c=static void serialTransmitInterrupt(uint8_t uart) {
serial.c: *serialRegisters[uart][SERIALDATA] = sendThisNext[uart];
serial.c: *serialRegisters[uart][SERIALDATA] = txBuffer[uart][txRead[uart]];
serial.c: serialRegisters[uart]->CTRLA &= ~(UART_INTERRUPT_MASK << 2); // TXCINTLVL
serial_device.h=uint8_t const serialBits[UART_COUNT][UART_BITS] = {{
serial_device.h:#define UART_INTERRUPT_MASK 0x03
... here it works?!
Does anyone know why the different behavior in regards to git grep on these systems? Is there a git config setting I have to enable, or is it a regression in git, or maybe there are some shell escaping problems on MSYS2?
Or in general - how can I get the same kind of git grep response on MSYS2, as I get it on Ubuntu?

Answer 1

I'll post this as an answer - after looking into git help grep, and brute forcing some switches, found that this works on MSYS2:
$ git grep -p --extended-regexp 'UART_INTERRUPT_MASK|SERIALDATA' -- '*.[ch]'
serial.c:#define SERIALDATA 0
serial.c=static void serialReceiveInterrupt(uint8_t uart) {
serial.c: rxBuffer[uart][rxWrite[uart]] = *serialRegisters[uart][SERIALDATA];
serial.c=static void serialTransmitInterrupt(uint8_t uart) {
serial.c: *serialRegisters[uart][SERIALDATA] = sendThisNext[uart];
serial.c: *serialRegisters[uart][SERIALDATA] = txBuffer[uart][txRead[uart]];
serial.c: serialRegisters[uart]->CTRLA &= ~(UART_INTERRUPT_MASK << 2); // TXCINTLVL
serial_device.h=uint8_t const serialBits[UART_COUNT][UART_BITS] = {{
serial_device.h:#define UART_INTERRUPT_MASK 0x03
and also this:
$ git grep -p --perl-regexp 'UART_INTERRUPT_MASK|SERIALDATA' -- '*.[ch]'
serial.c:#define SERIALDATA 0
serial.c=static void serialReceiveInterrupt(uint8_t uart) {
serial.c: rxBuffer[uart][rxWrite[uart]] = *serialRegisters[uart][SERIALDATA];
serial.c=static void serialTransmitInterrupt(uint8_t uart) {
serial.c: *serialRegisters[uart][SERIALDATA] = sendThisNext[uart];
serial.c: *serialRegisters[uart][SERIALDATA] = txBuffer[uart][txRead[uart]];
serial.c: serialRegisters[uart]->CTRLA &= ~(UART_INTERRUPT_MASK << 2); // TXCINTLVL
serial_device.h=uint8_t const serialBits[UART_COUNT][UART_BITS] = {{
serial_device.h:#define UART_INTERRUPT_MASK 0x03
So, use either --perl-regexp or --extended-regexp - and do not escape the pipe | with a backslash \, as one needs to do for usual grep.