incrond

由 datahunter 在二, 19/04/2016 - 09:57 發表

最後更新: 2019-08-07

介紹

* trigger commands when a file or directory event occurs

* incrond 不支援 Recursive directory

Install

# C6, C7: epel

yum install incron

獲得 program:

incrond
incrontab

Config:

/etc/incron.conf

Enable & Start Service

# C7

systemctl enable incrond --now

# C6

chkconfig incrond on

service incrond start

設定檔

/etc/incron.conf

# examined by incrond for system table files
system_table_dir = /etc/incron.d

# examined by incrond for user table files
user_table_dir = /var/spool/incron

# contains users allowed to use incron
allowed_users = /etc/incron/allow

incrontab

incrontab - a table manipulator for the incron system.

Help:

man incrontab

Permission

If /etc/incron.allow exists only users listed here may use incron

Otherwise if /etc/incron.deny exists only users NOT listed here may use incron

If none of these files exists everyone is allowed to use incron.

# Allow root only

echo root > /etc/incron.allow

Syntax

incrontab [-u user] [-f config] [-l | -r | -e | -t | -d]

CMD

# list

incrontab -l

# edit (/var/spool/incron/<USERNAME>)

incrontab -e

# Reloading the current table by incrond

incrontab --reload

requesting table reload for user 'root'...
request done

It is done through "touching" the table. This feature is for creating watches on newly created files (/var/spool/incron/FILE)

# List of supported event types(mask) (delimited by commas)

incrontab -t

IN_ACCESS
...
IN_CLOSE_WRITE(8)    # File opened for writing was closed
IN_CLOSE_NOWRITE  # File or directory not opened for writing was closed
...
IN_MOVED_TO
...
IN_DELETE
IN_DELETE_SELF
IN_CLOSE
...

incrontab 的 Format

Syntax

<path> <mask> <command>

path: an absolute filesystem path ( the same path may occur only once per table )

mask: an event mask (in symbolic or numeric form)

Path

* Path 不支援 *.txt 之類 (/root/test_folder/*.txt)

mask

IN_ACCESS
...
IN_CLOSE_WRITE
...

WILDCARDS

$$ dollar sign
$@ watched filesystem path
$# event-related file name
$% event flags (textually)
$& event flags (numerically)

Logging Event Script

Usage:

incrontab -l

/root/test_folder     IN_ALL_EVENTS     /root/scripts/mon.sh "$@ $# $& $%"

cat /root/scripts/mon.sh

#!/bin/bash
# 這裡的 "$@" 不是 incrond 的 "$@", 是 bash 的 "$@"
echo "$@" >> /tmp/log.txt

Create File (>>, >, touch) 時有的 event

echo "test" >> test.txt # 它們是一樣的 Event

echo "test" > test.txt

"/root/test_folder test.txt 8 IN_CLOSE_WRITE"
"/root/test_folder test.txt 256 IN_CREATE"
"/root/test_folder test.txt 32 IN_OPEN"
"/root/test_folder test.txt 2 IN_MODIFY"

touch test.txt

"/root/test_folder test.txt 8 IN_CLOSE_WRITE"
"/root/test_folder test.txt 256 IN_CREATE"
"/root/test_folder test.txt 32 IN_OPEN"
"/root/test_folder test.txt 4 IN_ATTRIB"

Append File(>>)

echo "test" >> test.txt

"/root/test_folder test2.txt 32 IN_OPEN"
"/root/test_folder test2.txt 2 IN_MODIFY"
"/root/test_folder test2.txt 8 IN_CLOSE_WRITE"

結論:

所有 create file 都有 IN_CLOSE_WRITE event

Delete File

"/root/test_folder test2.txt 512 IN_DELETE"

Move

# move in

"/root/test_folder test.txt 128 IN_MOVED_TO"

# move out

"/root/test_folder test.txt 64 IN_MOVED_FROM"

Read

cat test.txt

"/root/test_folder test.txt 32 IN_OPEN"
"/root/test_folder test.txt 16 IN_CLOSE_NOWRITE"

List

"/root/test_folder  1073741856 IN_OPEN,IN_ISDIR"
"/root/test_folder  1073741840 IN_CLOSE_NOWRITE,IN_ISDIR"

Example

# it will include hidden directories in the observation

/home IN_CREATE,dotdirs=true /usr/local/bin/abcd $#

# it will exclude sub-directories from the observation

/home IN_CREATE,recursive=false /usr/local/bin/abcd $#

Tips

1) 建議 mon Folder, 不要 mon File

vim FILE ":w" 係只能觸發一次 EVENT,
因為佢係 replace file 的 !! (.mySecRules.conf.swp -> mySecRules.conf)
replace 後 mon 就斷了, 因為 FILE 的 Inode 變了 (stat FILE)

應用: Reload apache when update modsecurity rules

incrontab -l

/etc/httpd/modsecurity.d IN_CLOSE_WRITE /root/scripts/modsecurity_reload.sh "$#"

modsecurity_reload.sh

#!/bin/bash
Log=/tmp/log.txt
if [ "$1" == "mySecRules.conf" ]; then
    echo `date` > $Log
    apachectl -t &>> $Log
    if [ $? -eq 0 ]; then
        service httpd reload
    fi
fi

Notes

# 觀察有無 reload

tail -f /var/log/httpd/error_log

應用: 利用 incron 行 git

incrontab -l

/home/vhosts/datahunter.org/realtime.txt IN_CLOSE_WRITE /home/vhosts/datahunter.org/scripts/realtime_git-it.sh

realtime_git-it.sh

#!/bin/bash

_trigger_file=/home/vhosts/datahunter.org/realtime.txt
_log=/var/log/git_log/realtime.log
_git_path=/home/vhosts/datahunter.org/public_html
_email='[email protected]'

# git setting
export HOME="/root"

# locking
_scriptname=$(basename $0)
_pidfile="/var/run/$_scriptname.pid"
exec 200>$_pidfile
flock -xn 200 || { echo -n "another instance is running"; exit 1; }
_pid=$$
echo $_pid
echo $_pid 1>&200

# code
if [ -s $_trigger_file ]; then
        echo "cleanup trigger_file & git"
        echo "$@" >> $_log

        # cleanup
        _msg=`cat $_trigger_file | tr '\n' ' ' | tr -d '\r'`
        echo -n "" > $_trigger_file

        # git
        cd $_git_path
        echo `date` >> $_log
        git add . >> $_log 2>&1
        git commit -m "$_msg" >> $_log 2>&1
        git config --file /root/.gitconfig credential.helper store >> $_log 2>&1
        git push >> $_log 2>&1

        # log file
        echo "=============================================" >> $_log

        # e-mail notification
        echo "git time: `date`" | mail -s'notification - server git' $_email
fi

# clean lock
rm -f $_lock

FAQ

IN_MODIFY 與 IN_CLOSE_WRITE

Why do inotify events fire more than once (IN_MODIFY)

when writing large files it would fire more than once.

That sounded fair

The IN_MODIFY event is emitted on a file content change (e.g. via the write() syscall)

while IN_CLOSE_WRITE occurs on closing the changed file.

It means each change operation causes one IN_MODIFY event

(it may occur many times during manipulations with an open file)

whereas IN_CLOSE_WRITE is emitted only once (on closing the file).

參考: http://datahunter.org/lock

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夢想家

incrond

介紹

目錄

Install

Enable & Start Service

設定檔

incrontab

Example

Tips

應用: Reload apache when update modsecurity rules

應用: 利用 incron 行 git

FAQ