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Is it possible to check the progress of running cp process? Some processes respond to various KILL signals so that you can check what is their status. I know that I can run cp with parameter -v but what if forgot to do that, cp is running for a very long time and I want to know which file is being copied, or how many were already copied.

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Duplicate -> unix.stackexchange.com/questions/65077/… –  yzT Mar 4 '13 at 10:54
I don't know if it's a duplicate, linked question is about parameters for cp, while my question is regarding cp that was already started, with no parameters –  Petr Mar 4 '13 at 15:26

6 Answers 6

up vote 10 down vote accepted

Yes, by running stat on target file and local file, and get a file size,

i.e stat -c "%s" /bin/ls

And you get the percentage of data copied by comparing the two value, that's it

In a very basic implementation that will look like this:

function cpstat()
  local pid="${1:-$(pgrep -xn cp)}" src dst
  [[ "$pid" ]] || return
  while [[ -f "/proc/$pid/fd/3" ]]; do
    read src dst < <(stat -L --printf '%s ' "/proc/$pid/fd/"{3,4})
    (( src )) || break
    printf 'cp %d%%\r' $((dst*100/src))
    sleep 1
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not intended to post a duplicate of your suggestion, so I added the code here. Hope you not mind. –  manatwork Mar 4 '13 at 11:13
@manatwork ah thanks, I was just being lazy in giving a complete example :-) –  warl0ck Mar 4 '13 at 12:03
Excellent, this is going in my toolbox on all servers! Thanks! –  ACK_stoverflow Jun 3 '13 at 22:55

When you're copying a lot of files, du -s /path/to/destination or find /path/to/destination | wc -l gives you an idea of how much has already been done.

You can find out which file is being copied with lsof -p1234 where 1234 is the process ID of cp. Under many systems, pgrep -x cp reports the process IDs of all running processes named cp. This may not be very useful as the order in which the files inside a given directory are copied is essentially unpredictable (in a large directory under Linux, ls --sort=none will tell you; with a directory tree, try find).

lsof -p1234 also tells you how many bytes cp has already read and written for the current file, in the OFFSET column.

Under Linux, there are IO usage statistics in /proc/$pid/io (again, use the PID of the cp process for $pidf). The rchar value is the total number of bytes that the process has read, and wchar is the number of bytes that the process has written. This includes not only data in files but also metadata in directories. You can compare that figure with the approximate figure obtained with du /path/to/source (which only counts file data). read_bytes and write_bytes only include what has been read or written from storage, i.e. it excludes terminal diagnostics and data already in cache or still in buffers.

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There are a few things you can do. You could attach strace to it to see what it's doing (output may be copious!):

strace -p [pid of cp]

or you could get lsof to tell you which files it currently has open:

lsof -p [pid of cp]

If you're running a big recursive cp, you could use pwdx to get the current working directory, which may give you some idea of how it's doing:

pwdx [pid of cp]
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On recent versions of Mac OS X you can just hit CTRL+T to see progress. From the OSX 10.6 man page for cp(1):

 "If cp receives a SIGINFO (see the status argument for stty(1)) signal,
 the current input and output file and the percentage complete will be
 written to the standard output."

Hitting CTRL+T is equivalent to signaling the current process with SIGINFO on BSD-ish machines, including OSX.

This works for dd(1) as well.

I don't think Linux has this SIGINFO mechanism, and don't see anything in the GNU man page for cp(1) about signals that can be used to report progress.

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What you can do is check the files at destination.

If your cp commands is something like cp -a <my_source> <my_dest_folder> I would check which files are already copied in <my_dest_folder> and each file size, so I can see the progress. If the <my_source> is a bit complex (several layers of directories) then a small script would be able to check the status. Although such a script could consume a bit of I/O that would then not be used by the cp process.

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One of my favorite tricks for this (under Linux) is to find out the PID of the cp process (using ps | grep cp or similar), and then to look in /proc/$PID/fd/ and /proc/$PID/fdinfo/.

$ cp -r y z
$ ls -l /proc/8614/fd
lrwx------ 1 jander jander 64 Aug  2 15:21 0 -> /dev/pts/4
lrwx------ 1 jander jander 64 Aug  2 15:21 1 -> /dev/pts/4
lrwx------ 1 jander jander 64 Aug  2 15:20 2 -> /dev/pts/4
lr-x------ 1 jander jander 64 Aug  2 15:21 3 -> /home/jander/y/foo.tgz
l-wx------ 1 jander jander 64 Aug  2 15:21 4 -> /home/jander/z/foo.tgz

This will show you what files the process has open. If you want to see how far into the file the process is...

$ cat /proc/8614/fdinfo/3
pos:    105381888
flags:  0500000

the pos parameter is the position of the read (or write) pointer, in bytes.

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