进入相应SVN仓库hooks目录，编辑文件pre-commit

#!/bin/sh

# PRE-COMMIT HOOK
#
# The pre-commit hook is invoked before a Subversion txn is
# committed. Subversion runs this hook by invoking a program
# (script, executable, binary, etc.) named 'pre-commit' (for which
# this file is a template), with the following ordered arguments:
#
# [1] REPOS-PATH (the path to this repository)
# [2] TXN-NAME (the name of the txn about to be committed)
#
# [STDIN] LOCK-TOKENS ** the lock tokens are passed via STDIN.
#
# If STDIN contains the line "LOCK-TOKENS:\n" (the "\n" denotes a
# single newline), the lines following it are the lock tokens for
# this commit. The end of the list is marked by a line containing
# only a newline character.
#
# Each lock token line consists of a URI-escaped path, followed
# by the separator character '|', followed by the lock token string,
# followed by a newline.
#
# The default working directory for the invocation is undefined, so
# the program should set one explicitly if it cares.
#
# If the hook program exits with success, the txn is committed; but
# if it exits with failure (non-zero), the txn is aborted, no commit
# takes place, and STDERR is returned to the client. The hook
# program can use the 'svnlook' utility to help it examine the txn.
#
# On a Unix system, the normal procedure is to have 'pre-commit'
# invoke other programs to do the real work, though it may do the
# work itself too.
#
# *** NOTE: THE HOOK PROGRAM MUST NOT MODIFY THE TXN, EXCEPT ***
# *** FOR REVISION PROPERTIES (like svn:log or svn:author). ***
#
# This is why we recommend using the read-only 'svnlook' utility.
# In the future, Subversion may enforce the rule that pre-commit
# hooks should not modify the versioned data in txns, or else come
# up with a mechanism to make it safe to do so (by informing the
# committing client of the changes). However, right now neither
# mechanism is implemented, so hook writers just have to be careful.
#
# Note that 'pre-commit' must be executable by the user(s) who will
# invoke it (typically the user httpd runs as), and that user must
# have filesystem-level permission to access the repository.
#
# On a Windows system, you should name the hook program
# 'pre-commit.bat' or 'pre-commit.exe',
# but the basic idea is the same.
#
# The hook program typically does not inherit the environment of
# its parent process. For example, a common problem is for the
# PATH environment variable to not be set to its usual value, so
# that subprograms fail to launch unless invoked via absolute path.
# If you're having unexpected problems with a hook program, the
# culprit may be unusual (or missing) environment variables.
#
# Here is an example hook script, for a Unix /bin/sh interpreter.
# For more examples and pre-written hooks, see those in
# the Subversion repository at
# http://svn.apache.org/repos/asf/subversion/trunk/tools/hook-scripts/ and
# http://svn.apache.org/repos/asf/subversion/trunk/contrib/hook-scripts/

REPOS="$1"
TXN="$2"
NEED_LEN=8

# Make sure that the log message contains some text.
SVNLOOK=/usr/bin/svnlook
tmp_msg=`$SVNLOOK log -t "$TXN" "$REPOS"`
tmp_msg_len=${#tmp_msg}

# 中文情况下 长度判断是无效的
if (( ${tmp_msg_len} < ${NEED_LEN} ));then
echo "-->No Allow Empty MESSAGE! Write Message And Length Must > ${NEED_LEN} <--" >&2
exit 1
fi

# Check that the author of this commit has the rights to perform
# the commit on the files and directories being modified.
#commit-access-control.pl "$REPOS" "$TXN" commit-access-control.cfg || exit 1

# All checks passed, so allow the commit.
exit 0