Change logging directory in Google glog

Question

How can I change the output directory in Google glog?

I only found google::SetLogDestination(google::LogSeverity, const char* path)

tried it with:

google::SetLogDestination(ERROR, "C:\\log\\error.log);
google::InitGoogleLogging("Test");  

LOG(ERROR) << "TEST";

but nothing was written!

Btw.: if you suggest another lightweight, easy to use and thread safe library please let me know!

Thx for any help!

Are you sure that the escaping is working correctly in that path string? What it you try setting the log dir at the command line with: `GLOG_log_dir=C:\log\error.log ./your_application` — NicholasM, Nov 16 '13 at 08:12

score 14 · Accepted Answer · answered Sep 13 '14 at 15:37

You can also do one of the following:

Pass the log directory as a commandline argument as long as you have the GFlgas library installed:

./your_application --log_dir=/some/log/directory

If you don't want to pass it in the commandline and instead set it in the source:

FLAGS_log_dir = "/some/log/directory";

If the Google gflags library isn't installed you can set it as an environment variable:

GLOG_log_dir=/some/log/directory ./your_application

score 5 · Answer 2 · answered Oct 16 '13 at 06:21

Here is the test what I did, you may try it,

#include <glog/logging.h>

using namespace std;

int main(int /*argc*/, char** argv)
{
    FLAGS_logtostderr = true;
    google::SetLogDestination(google::GLOG_INFO,"c:/lovelyGoogle" );
    google::InitGoogleLogging(argv[0]);

    LOG(INFO) << "This is INFO";
    LOG(WARNING) << "This is WARNING";
    LOG(ERROR) << "This is Error";

    system("pause");
    return 0;
}

Tested under Visual studio 2012, google-glog 0.3.3 on Windows 7.
It generated lvoelyGoogle20131016-141423.5160 on my C driver.
If you set FLAGS_logtostderr = false, the log file will not be generated,

I believe you have already read this (well, I have no comment on it)

hope this helpful, good luck.

PS: I have tested on QtCreator (Qt5.1) as well on Windows7, nothing output. I have no idea how to fix it now.

@CCC Note that if, for instance, you wish to place it in a "dedicated" directory - this directory MUST exists (the glog code won't create during run-time of the program). For example: If you wish that the log will be saved to: `c:/yourDir/lovelyGoogle` (note the `yourDir` addition), than `yourDir` needs to exist prior to your program execution. — Guy Avraham, Sep 15 '18 at 08:16

angelo.mastro · Answer 3 · 2021-10-22T14:41:44.537

In my terrifying experience with this library I came to see that this flag FLAGS_log_dir and this function google::SetLogDestination() compete with each other. Wonderful.

I learned that you can use either but not both.

option 1: use flags

FLAGS_log_dir=/path/to/your/logdir
google::InitGoogleLogging(exec_name.c_str());

and generate a bunch of files named your_exec.some_number.machine_name.log.log_severity.... and their respective symbolic link inside the /path/to/your/logdir. A pair of files will be generated for each log_severity you have used in your program (INFO, WARNING, ERROR, FATAL). Fun fact: INFO files contain everything, WARNING files contain everything from warning downwards, and so on. God knows why these symlinks are needed.

option 2: use file names

std::string log_dir = "/path/to/log/dir";
for (int severity = 0; severity < google::NUM_SEVERITIES; ++severity) {
   std::string fpath = fs::path(fs::path(log_dir) / fs::path(exec_name).filename());
   google::SetLogDestination(severity, fpath.c_str());
   google::SetLogSymlink(severity, "");
}
google::InitGoogleLogging(exec_name.c_str());

where fs is the filesystem library of c++17. This is send all logs to the same file (just one, not many) and finally remove that annoying symbolic link.

score 1 · Answer 4 · answered Feb 08 '14 at 15:50

1

I use this:

fLS::FLAGS_log_dir = "c:/Documents/logs";

answered Feb 08 '14 at 15:50

Adrian

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score 1 · Answer 5 · answered May 25 '23 at 02:05

This solution works for me:

FLAGS_log_dir = "./log/";
FLAGS_alsologtostderr = true;
google::InitGoogleLogging(argv[0]);

FLAGS_log_dir sets the preferred logging destination, as it says.
FLAGS_alsologtostderr sets if you also wanna log to stderr, while saving logs into a separate file for review.

Note:

Don't set FLAGS_logtostderr to true if you want your log be written to both the file and stderr, that way use FLAGS_alsologtostderr instead as I did.

Tested under Clion 2023.1.3, macOS 13.3.1 (a) (22E772610a), glog v0.6.0

Change logging directory in Google glog

5 Answers5