frenum(1) General Commands Manual frenum(1)
NAME
frenum - renumbers multiple file names
SYNOPSIS
frenum [options] [file...]
DESCRIPTION
frenum renumbers the file names supplied according to the specified
options. The default action is to number the files starting from 1,
which is probably not what the average user really wants; which means
that some options must usually be specified. The starting number, the
increment, the zero-filled field width, any required prefix or suffix,
can all be specified. If the existing file name's alpha component is
required to be retained, that can be specified, including truncation
point and any case modifications (upper, lower, initial-caps) that
might be desired.
No files will be overwritten; if there is a name clash, frenum will
gracefully re-compute the next file name in the series. If no files
are found on the command line, the standard input is read. To allow
usage in a pipeline initiated with find, all non-regular files are
ignored without error. The pathname up to the last slash is also left
as-is; the transformation rules are applied only to the file name.
For example, to renumber files in directory "img" to preserve the first
four characters, initial-uppercased, use a three-digit number and
change the extension to ".jpg":
find img -print | frenum --Trunc 4 --Case i --Width 3 -.jpg
If the original name was: The result would be:
img/ASHGROVE.JPEG --> img/Ashg001.jpg
img/ASIMOV_39.JPG --> img/Asim002.jpg
img/woodland2003.jpeg --> img/Wood003.jpg
img/woodland99.jpeg --> img/Wood004.jpg
img/xenia.jfif --> img/Xeni005.jpg
To do the same thing, but begin numbering at 100 in increments of 10:
find img -print | frenum -t4 -ci -w3 -.jpg -b100 -n10
OPTIONS
-n, --Num[ber] nn
Increment is nn, discard original name (default is 1). Use -n0
to turn off numbering; file name clashes may result.
-b, --Begin nn
Start with nn (otherwise defaults to 1).
-w, --Width nn
Zero-filled field width. This really must be given, since an
unformatted numeric file name is really ugly. The maximum width
is 10 and the minimum is -20. If a negative width is specified,
it is taken as the fixed width of the entire file name
(including all prefixes, but not including any explicit
extension or suffix). Consider the following examples:
Original Name Using "-w4" Using "-w-8"
------------- ------------ ------------
Jack Jack0001 Jack0001
Jem Jem0002 Jem00002
Jeremy Jeremy0003 Jeremy03
Julianne Julianne0004 Juliann4
Note that the name is truncated to acommodate the number.
-t, --Trunc[ate] nn
Delete from nn or first non-alpha. If you want to preserve all
alphas, you could use -t99 or something like that.
-x, --Skip nn
Drop the first nn characters of the file name before applying
any other rules. The --Skip and --Trunc options together define
a segment (substring) of the original file name.
-p, --Prefix aaa
Add a string in front. Usually not done in conjunction with the
--Truncate option, but you can if you want to.
-s, --Suffix aaa
Add a string at the end. This is in addition to any existing
suffix or extension. If you want to replace the existing
extension, don't use this; use --Extension instead.
-., --Extension aaa
Suffix starting with a dot. If there is already an extension,
it will be replaced. If there are multiple extensions, the
rearmost one will be replaced.
-/, --Translate aaa/bbb
Translate characters. Each matching character in the string aaa
is replaced by its same-position character in bbb. The two
strings must be of equal length. For example, using the
command:
frenum -t99 -/aei/xyz -w-7
alpha --> xlphx01
beta --> bytx002
phi --> phz0003
This translation applies only to existing components of the file
name, not to any supplied prefixes or suffixes.
-c, --Case [ lower | Upper | initial-caps ]
Adjust the case of the alphabetic portion of the file name.
-o, --Opt[imal]
Permit only alphanumerics, -, +, ., and _. Use this option if
your file names have got rather garbaged; you'll end up with
nice clean names with no nasty characters in them. If you want
only to optimize the file names and nothing else, use:
frenum --Optimal --Number 0
and perhaps --Case initial-caps to beautify a bit more.
-z, --Zap[-Numerics]
Delete all non-alphas. You would use this to remove numerics
interspersed with alphas in the file names. If you're simply
renumbering, of course, you won't need this; you will probably
use --Trunc.
-d, --Dirs[-Also]
Don't ignore directory names. Use with caution, specially if
you are also piping in the contents of directories. It is
possible that a directory name might be changed, and a later
pathname specifies a directory which no longer exists. This is
best used interactively with wildcards.
-l, --List[-Only]
Don't do it, just report what would happen. Strongly
recommended the first time you prepare a command line.
-k, --Keep-Going
Don't stop on file errors, go to next file name. This will be
needed only if the numbering option is turned off, or you are
trying to renumber files some of which you don't own.
-v, --Ver[sion]
Shows the version of the program and its creation date.
-h, --Help
Shows a help page which is a summary of the options. If you
include "2" as a parameter, i.e. "-h2", a second help page gives
a quick summary of other useful information.
-u, --Verbose
The opposite of --Quiet. Only needed if you want verbosity in a
pipeline; it's the default when output is to the screen.
-q, --Quiet, --Silent
Don't give chatty status messages. However, each renumbered
file will still be echoed to the standard output, and errors are
sent to the error output. This is the default if output is to a
pipe. It is ignored if you specify the --List option.
-, --Standard-input
Read stdin for more file names. This is not normally necessary
unless at least one file name has already been specified on the
command line.
ENVIRONMENT
No environment variables are used.
SEE ALSO
mv(1)
DIAGNOSTICS
If you give an invalid option it may give you some feedback. However,
use of the --List option is strongly recommended to avoid unexpected
results. Specific messages include:
Unrecognized option "x", possibly meant to be "y"
You have probably mis-spelled a long option.
"Case" option argument is invalid
The argument to --Case must be one of "u", "l", or "i".
"Translate" option argument has no replacement section
"Translate" option's find and replace parts of different size
Translate requires an argument which is two charsets separated by a
slash.
Width value is not in the allowed range
Field too fat.
Numeric option x has improper value y
We're expecting a number. Use digits. And not too many of them.
Number too large for field
You asked for a fixed-width name, but the digits of the number alone
are bigger than that. Give it more width or reduce the number.
BUGS
Report bugs to: Renuk de Silva (renuk007@users.sourceforge.net). No
new or interesting bugs have been reported yet.
COPYRIGHT
Copyright (C) 2008 by Renuk de Silva. Modifications copyright (C)
2025-2026 by Brian Lindholm. This program is free software; you can
use it, redistribute it, and/or modify it under the terms of the GNU
General Public License as published by the Free Software Foundation;
either version 3, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
littleutils 2026 Jan 01 frenum(1)
littleutils 1.4.0 - Generated Wed Feb 18 07:20:29 CST 2026