How to redirect Valgrind's output to a file?

Question

While working with Valgrind tool, i need to log the details produced by valgrind tool. How can I accomplish that? I tried something like,

 valgrind a.out | test

and

 valgrind a.out > test

It gave just the program's output and not the valgrind memory error,leak information. Even i am getting like this if the program requires no user interaction (i.e. giving input). If the program need user input even that thing itself won't work.

How can I do this?

Have you tried redirecting both stout and stderr? `valgrind a.out &> file` — sidyll, Dec 02 '11 at 11:58

score 456 · Accepted Answer · edited Sep 26 '12 at 08:46

456

valgrind --log-file="filename"

edited Sep 26 '12 at 08:46

fancyPants

50,732
33
89
96

answered Sep 14 '12 at 08:26

Vasileios Lekakis

5,492
2
15
17

4

this saves just stderr, is it possible to save both stderr and stdout into same file in the same order as is written in terminal ( i.e. to keep coherence between outputs of tested program and error reported by valgrind) ? – Prokop Hapala Jan 20 '19 at 11:14

score 90 · Answer 2 · answered Dec 02 '11 at 11:59

90

By default, Valgrind writes its output to stderr. So you need to do something like:

valgrind a.out > log.txt 2>&1

Alternatively, you can tell Valgrind to write somewhere else; see http://valgrind.org/docs/manual/manual-core.html#manual-core.comment (but I've never tried this).

answered Dec 02 '11 at 11:59

Oliver Charlesworth

267,707
33
569
680

5

Thanks a lot :). It worked. Can you please tell me what's with that "2>&1"? – Dinesh Dec 02 '11 at 12:05
11

@Dinesh: I suggest reading http://www.gnu.org/software/bash/manual/bashref.html#Redirections, which describes the bizarre Bash syntax for doing redirections! – Oliver Charlesworth Dec 02 '11 at 12:08
17

NOTE: that this suggestion will also send `a.out`'s output to the same log file. If you want to save valgrind's output to the logfile *without* `a.out`'s, you should use the `--log-file` option suggested by Lex. – edam Oct 01 '13 at 13:34
This is also a great answer for debugging memory leaks! – Free Url Nov 25 '17 at 00:26
If you want to pipe output to another command: `valgrind ./struct -v --leak-check=full 2>&1 | nc -N paste.ubuntu.ir 1337` – EsmaeelE Feb 10 '21 at 00:13

score 12 · Answer 3 · answered Mar 10 '15 at 15:46

12

You can also set the options --log-fd if you just want to read your logs with a less. For example :

valgrind --log-fd=1 ls | less

answered Mar 10 '15 at 15:46

Ziad

419
3
7
15

score 5 · Answer 4 · answered Dec 12 '20 at 15:58

In addition to the other answers (particularly by Lekakis), some string replacements can also be used in the option --log-file= as elaborated in the Valgrind's user manual.

Four replacements were available at the time of writing:

%p: Prints the current process ID
- valgrind --log-file="myFile-%p.dat" <application-name>
%n: Prints file sequence number unique for the current process
- valgrind --log-file="myFile-%p-%n.dat" <application-name>
%q{ENV}: Prints contents of the environment variable ENV
- valgrind --log-file="myFile-%q{HOME}.dat" <application-name>
%%: Prints %
- valgrind --log-file="myFile-%%.dat" <application-name>

How to redirect Valgrind's output to a file?

4 Answers4

Linked