Makefile : Clock skew detected

Question

My problem is whenever I try to compile using Makefile I get the following :

make: Warning: File `Board.c' has modification time 1.3e+03 s in the future
gcc -Wall -c -Wvla -lm Board.c -o Board.o
gcc -Wall -c -Wvla -lm PlayBoard.c -o PlayBoard.o
gcc -lm ErrorHandle.o Board.o PlayBoard.o -g -o PlayBoard
make: warning:  Clock skew detected.  Your build may be incomplete.

My Makefile is :

CC = gcc
FLAGS = -Wall -c -Wvla

PlayBoard: ErrorHandle.o Board.o PlayBoard.o
    $(CC) -lm ErrorHandle.o Board.o PlayBoard.o -g -o $@

PlayBoard.o: PlayBoard.c Board.o
    $(CC) $(FLAGS) -lm PlayBoard.c -o $@

Board.o : ErrorHandle.o Board.c Board.h
    $(CC) $(FLAGS) -lm Board.c -o $@

.PHONY : clean

clean:
    rm -f Board.o PlayBoard.o PlayBoard

all : PlayBoard

Thank you for your help.

Check the modification time of `Board.c`, it appears that you may have copied this from another source when in the time of creation is ahead of your machin. One solution could be run `touch Board.c` to set the modification time to current time — another.anon.coward, Dec 06 '12 at 14:27
This isn't related to C in any way. This is a warning issued by `make`. — alk, Jan 31 '17 at 08:37
@alk: I can't see any tacit evidence that would warrant this question to be protected. There aren't a lot of answers from low-rep members and there doesn't seem to be any immediate danger of this question being suddenly very popular and getting a lot of attention, either. — Makoto, Jan 31 '17 at 08:41

score 39 · Answer 1 · edited Oct 01 '14 at 09:51

39

A possible solution is to touch every file in the source tree in order to update time-stamps:

Go to the root of the sub-tree an do:

find . -exec touch {} \;

Then make clean and retry compilation.

edited Oct 01 '14 at 09:51

ani627

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answered Sep 25 '13 at 22:44

sblob

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Works every time. Thank you! – steadweb Jun 01 '16 at 16:27
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Doing so let's you then always and ever compile all an everything, not just only the source files which had been touched due to code changes. At least for a large code base this probably is not what you want,. – alk May 11 '17 at 05:01

score 27 · Answer 2 · answered Dec 06 '12 at 15:05

27

As denoted in a comment by stijn the message "Clock skew detected" is most commonly given if compiling sources located on an NFS mount and the NFS server's clock runs ahead the client's clock doing the compilation.

answered Dec 06 '12 at 15:05

alk

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Is there a solution to this? My source files are on an nfs server that appears to be slightly ahead. My dev machine and the nfs server are VM's on seperate domains so I may never get clocks exact – TSG Feb 28 '15 at 01:04
@Telium : You might want to run an N(erwork)T(ime)P(rotocol) client on both machines on a regular base? – alk Aug 04 '15 at 06:51

score 3 · Answer 3 · answered Jul 16 '13 at 20:06

I saw this in Eclipse a couple of times as well when doing some work on one of the University computers here. My data drive was a network drive and the clock difference between the network drive and the local machine was off.

Switching my workspace to a location on the local machine (C drive) fixed the problem

Makefile : Clock skew detected

3 Answers3

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