如何在Linux系统下安装svn， 这里暂不介绍，请看本文下方的相关教程，在svn安装目录下有个hooks文件夹， 修改其中的pre-commit.tmpl文件；
cp pre-commit.tmpl pre-commit
修改pre-commit文件
#!/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 fo
# 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 neithe
# 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="$2"
# Make sure that the log message contains some text.
SVNLOOK=/usr/bin/svnlook
# 添加以下5行代码
LOGMSG=`$SVNLOOK log -t "$TXN" "$REPOS" | grep "[a-zA-Z0-9]" | wc -c`
if [ "$LOGMSG" -lt 10 ];then
echo "提交失败： 注释不能低于10个字符" 1>&2
exit 1
fi
# 以下全部注释掉
# $SVNLOOK log -t "$TXN" "$REPOS" |
# grep "[a-zA-Z0-9]" > /dev/null || exit 1
# Check that the author of this commit has the rights to perform
# the commit on the files and directories being modified.
#commit-access-control.pl "$REPOS" "$TXN" commit-access-control.cfg || exit 1
# All checks passed, so allow the commit.
#exit 0
其实以上的去掉注释部分只有几行代码：
#!/bin/sh
REPOS="$1"
TXN="$2"
SVNLOOK=/usr/bin/svnlook # 同pre-commit.tmpl文件中的SVNLOOK
LOGMSG=`$SVNLOOK log -t "$TXN" "$REPOS" | grep "[a-zA-Z0-9]" | wc -c`
if [ "$LOGMSG" -lt 10 ];then
echo "提交失败： 注释不能低于10个字符" 1>&2
exit 1
fi
然后 给pre-commit文件添加755权限：
chmod 755 pre-commit 或 chmod x pre-commit
如果没有添加权限， 则会报：
Commit blocked by pre-commit hook (exit code 255) with no output 错误， 请注意。
更多Subversion (SVN)相关教程见以下内容
：
Ubuntu 14.04 下搭建SVN服务器 SVN:// http://www.linuxidc.com/Linux/2015-01/111956.htm
CentOS 7下安装iF.svnadmin实现Web方式管理SVN（源码安装） http://www.linuxidc.com/Linux/2016-08/134214.htm
CentOS7.2 编译安装SVN1.9.5客户端 http://www.linuxidc.com/Linux/2017-03/141387.htm
SVN 服务器搭建步骤及使用实战 http://www.linuxidc.com/Linux/2017-01/139282.htm
CentOS 7下搭建配置SVN服务器 http://www.linuxidc.com/Linux/2017-05/144254.htm
CentOS 7.2下Nginx MySQL PHP-FPM SVN配置Walle自动化部署系统详解 http://www.linuxidc.com/Linux/2016-11/137703.htm
基于腾讯CentOS 7云服务器搭建SVN版本控制库 http://www.linuxidc.com/Linux/2017-05/144244.htm
CentOS 7.1 下SVN安装与配置 http://www.linuxidc.com/Linux/2016-12/138637.htm
CentOS 6.8 搭建SVN（版本控制系统）及SVN的使用 http://www.linuxidc.com/Linux/2017-04/143093.htm
Linux上手动搭建svn服务器 http://www.linuxidc.com/Linux/2017-12/149777.htm
