> gcc -Wall -Wextra -O3 -std=c11 -pthread -D_GNU_SOURCE -D_DEFAULT_SOURCE -c krep.c -o krep.o
   > make: gcc: No such file or directory
   > make: *** [Makefile:86: krep.o] Error 127

❯ ./result/bin/krep 'krep' pkgs/by-name/kr/krep/package.nix
Warning: Line printing forces single-threaded mode (-t ignored).
pkgs/by-name/kr/krep/package.nix:  pname = "krep";
pkgs/by-name/kr/krep/package.nix:    repo = "krep";
pkgs/by-name/kr/krep/package.nix:    homepage = "https://github.com/davidesantangelo/krep";
pkgs/by-name/kr/krep/package.nix:    changelog = "https://github.com/davidesantangelo/krep/releases/tag/v${finalAttrs.version}";
--- Total Matches: 4 ---
Search completed in 0.0001 seconds (14.11 MB/s)
Search details:
  - File size: 0.00 MB (952 bytes)
  - Pattern length: 4 characters
  - Pattern type: Literal text
  - Execution: Single-threaded (1 thread)
  - Algorithm used: Boyer-Moore-Horspool
  - SIMD Available: No (Using scalar algorithms)
  - Case-sensitive search

$ seq 1 10000 > /tmp/x && krep '11' /tmp/x | head -n20
Warning: Line printing forces single-threaded mode (-t ignored).
/tmp/x:11
/tmp/x:110
/tmp/x:111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128

error: builder for '/nix/store/7bsiz0pd1b837nw67gdnirkfzjp36d1g-krep-0.3.3.drv' failed with exit code 2;
       last 19 log lines:
       > Running phase: unpackPhase
       > unpacking source archive /nix/store/bywhfcgs7zdndd98g4q0nys8zas4rzz9-source
       > source root is source
       > Running phase: patchPhase
       > Running phase: updateAutotoolsGnuConfigScriptsPhase
       > Running phase: configurePhase
       > no configure script, doing nothing
       > Running phase: buildPhase
       > build flags: SHELL=/nix/store/58br4vk3q5akf4g8lx0pqzfhn47k3j8d-bash-5.2p37/bin/bash CC=cc ENABLE_ARCH_DETECTION=0
       > cc -Wall -Wextra -O3 -std=c11 -pthread -D_GNU_SOURCE -D_DEFAULT_SOURCE -c krep.c -o krep.o
       > cc -Wall -Wextra -O3 -std=c11 -pthread -D_GNU_SOURCE -D_DEFAULT_SOURCE -o krep krep.o
       > Running phase: checkPhase
       > gcc -Wall -Wextra -O3 -std=c11 -pthread -D_GNU_SOURCE -D_DEFAULT_SOURCE -DTESTING -c test/test_krep.c -o test/test_krep.o
       > gcc -Wall -Wextra -O3 -std=c11 -pthread -D_GNU_SOURCE -D_DEFAULT_SOURCE -DTESTING -c test/test_regex.c -o test/test_regex.o
       > gcc -Wall -Wextra -O3 -std=c11 -pthread -D_GNU_SOURCE -D_DEFAULT_SOURCE -DTESTING -o test_krep test/test_krep.o test/test_regex.o krep.o
       > /nix/store/s40y31bdn82sj6daaxid1bn3p7la03lv-binutils-2.43.1/bin/ld: krep.o: in function `main':
       > krep.c:(.text.startup+0x6c0): multiple definition of `main'; test/test_krep.o:test_krep.c:(.text.startup+0x0): first defined here
       > collect2: error: ld returned 1 exit status
       > make: *** [Makefile:91: test] Error 1
       For full logs, run 'nix log /nix/store/7bsiz0pd1b837nw67gdnirkfzjp36d1g-krep-0.3.3.drv'.

$ seq 1 100000 > /tmp/x; pat=1; LANG= time krep $pat /tmp/x | wc -l; LANG= time rg $pat /tmp/x | wc -l
Warning: Line printing forces single-threaded mode (-t ignored).
1.94user 0.00system 0:01.95elapsed 99%CPU (0avgtext+0avgdata 3328maxresident)k
0inputs+0outputs (0major+400minor)pagefaults 0swaps
40963
0.00user 0.00system 0:00.00elapsed 80%CPU (0avgtext+0avgdata 6656maxresident)k
0inputs+0outputs (0major+698minor)pagefaults 0swaps
40952