# Create a dummy cookie jar larger than 4KiB.
$ printf '%s\tFALSE\t/\tTRUE\t2147483647\to\tfoo=bar\n' {0..200}.example.com > x

# Run curl reading & writing that cookie jar.
$ strace -e'!signal' curl https://google.com --cookie x --cookie-jar x
...
openat(AT_FDCWD, "x", O_WRONLY|O_CREAT|O_TRUNC, 0666) = 4
fstat(4, {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
write(4, "# Netscape HTTP Cookie File\n# ht"..., 4096) = 4096
write(4, "e.com\tFALSE\t/\tTRUE\t2147483647\to\t"..., 4096) = 4096
write(4, "LSE\t/\tTRUE\t2147483647\to\tfoo=bar\n"..., 1884) = 1884
close(4)                                = 0
...