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SUMMER(1) Chiark-utils-bin SUMMER(1)


summer - print checksum and system metainformation for files


summer -ACDbfqtx [startpoint...]


summer prints the MD5 checksum of the contents, and the system metainformation (ownership, permissions, timestamps, etc.), for a file, or recursively for a whole directory tree.

Each command line argument should be a file or directory to be processed; if it is a directory then it will be processed and then its contents will also be processed, recursively. If no startpoints are specified on the command line then summer will read a list of newline-separated startpoints from standard input.

Since summer correctly handles devices, FIFOs and other non-regular files it is useful for generating and comparing summaries of arbitrary directory trees where md5sum alone would not be.


summer prints one line of information for each filesystem object it processes. Each line has the following columns:

MD5 checksum (in hex) or file type information
Size of file in bytes
File access rights (in octal)
User ID of owner (in decimal)
Group ID of owner (in decimal)
atime (time of last access, decimal time_t)
mtime (time of last modification)
ctime (time of last status change)

For regular files, the first column is the md5sum. For directories, pipes, symlinks and sockets it is the literal string dir, mountpoint, pipe, symlink or socket as appropriate. For devices it begins with c for character or b for block devices, followed by the device number as a single 32 bit hex number and as four separate 8 bit decimal numbers (most significant first).

Note that any bytes in the filename other than printing 7-bit ASCII are escaped using \xNN syntax, where NN are two hex digits; backslashes are also escaped in this way. This makes the output unambiguous. Filenames will be relative if the relevant startpoint was relative, and absolute if it was absolute.

For symlinks the filename column is followed by ` -> ' (note the spaces) and the target of the link, again escaped, as above.


Do not print the atime (time of last access). The atime column will be omitted.
Do not print the ctime (time of last status change). The ctime column will be omitted.
Do not print the mtime (time of last modification). The mtime column will be omitted.
Do not print directory sizes. The size column for directories will read dir.
Do not print mtime (time of last modification) for symbolic links. The mtime field for symbolic links will read link.
Do not print any times for special files, symlinks, sockets, or fifos. The atime, mtime and ctime fields for these objects will read char, block, link, sock or pipe instead.
Include information about errors encountered (for example, unreadable files) in the output, and continue processing. The default is to print error information to standard error and stop immediately an error is encountered.
Do not cross mountpoints while recursing into subdirectories. Startpoints which are mountpoints are descended into.
Suppress the progress information which summer normally prints to standard error.
Set the field separator between the information and the filename to a tab character (default is space).
Normally any errors (problems accessing files including nonexistent startpoings, and the like) are fatal; an error message is reported to stderr.

With -f errors are nonfatal and the problems are reported inline. The filesystem object with the problem is reported in the normal way except that instead of the checksum, the string \[problem[: details]] appears. Fields whose value could not be determined are printed as ?.

Print a brief usage message to stderr (and do nothing else, exiting nonzero).


If the first character in the line is \[, then the first (checksum or type) field is everything until the first subsequent ]; this may be of variable length and will be followed by one or more spaces. Otherwise the first field has a fixed width: 64 characters, the size of an MD5 checksum represented in hex, and is followed by a single space.

The metadata fields are space-separated but are also space-padded to a minimum width: 10 characters for sizes and times and ids; 4 characters for the mode.

The filename field, and optional link target information, are of variable length, but they are escaped so that they do not contain spaces.


summer is
Copyright (C) 2003-2007 Ian Jackson <>

This manpage was written by Peter Maydell and subsequently improved by Ian Jackson. It is
Copyright (C) 2006 Peter Maydell <>
Copyright (C) 2007 Ian Jackson <>

This is free software, distributed under the GNU General Public Licence, version 3 or (at your option) any later version; see /usr/share/doc/chiark-utils-bin/copyright or /usr/share/common-licenses/GPL-3 for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

December 2006 Debian