[[PageOutline]]

 * [http://miya0.dyndns.org/pc/settei/crontab.html crontabの書き方]
 * [http://www.server-memo.net/tips/crontab.html crontabの書き方 — server-memo.net]

 = 遅延実行 =
 * [http://d.hatena.ne.jp/Oswald/20090117/1232175381 cronスクリプトをバックグラウンドで実行するときの注意点 - ハッカー現役続行]
   * これを解決するには、このプロセスがopenしているファイルディスクリプタをcloseします。
{{{
sleep 15 >/dev/null 2>&1 &
}}}

 = 遅延実行テスト =
 * crontab -l
{{{
*/2 * * * * /home/mitty/crontest
}}}

 == フォアグラウンド sleep ==
 * /home/mitty/crontest
{{{
#!/bin/sh

export LANG=C


touch /tmp/$$.`date +%T`
ls -l /tmp

sleep 60;

touch /tmp/$$.`date +%T`
ls -l /tmp
}}}

 * pstree -ap
{{{
  ├─cron,662
  │   └─cron,2325
  │       ├─sendmail,2332 -i -FCronDaemon -oem mitty
  │       │   └─postdrop,2333 -r
  │       └─sh,2326 -c /home/mitty/crontest
  │           └─crontest,2327 /home/mitty/crontest
  │               └─sleep,2331 60
}}}

 * mail
{{{
Mail version 8.1.2 01/15/2001.  Type ? for help.
"/var/mail/mitty": 1 message 1 new
>N  1 root@lucid.mitty.  Tue May 18 16:07   25/937   Cron <mitty@lucid> /home/mi
&
Message 1:
From mitty@lucid.mitty.jp  Tue May 18 16:07:01 2010
X-Original-To: mitty
From: root@lucid.mitty.jp (Cron Daemon)
To: mitty@lucid.mitty.jp
Subject: Cron <mitty@lucid> /home/mitty/crontest
Content-Type: text/plain; charset=ANSI_X3.4-1968
X-Cron-Env: <SHELL=/bin/sh>
X-Cron-Env: <HOME=/home/mitty>
X-Cron-Env: <PATH=/usr/bin:/bin>
X-Cron-Env: <LOGNAME=mitty>
Date: Tue, 18 May 2010 16:06:01 +0900 (JST)

total 0
-rw-r--r-- 1 mitty mitty  0 May 18 16:06 2327.16:06:01
drwx------ 2 mitty mitty 22 May 18 13:51 ssh-qAiiolp854
total 0
-rw-r--r-- 1 mitty mitty  0 May 18 16:06 2327.16:06:01
-rw-r--r-- 1 mitty mitty  0 May 18 16:07 2327.16:07:01
drwx------ 2 mitty mitty 22 May 18 13:51 ssh-qAiiolp854
}}}

 === with mail command ===
 * /home/mitty/crontest
{{{
#!/bin/sh

export LANG=C


touch /tmp/$$.`date +%T`
ls -l /tmp 2>&1 | mail $LOGNAME

sleep 60;

touch /tmp/$$.`date +%T`
ls -l /tmp 2>&1 | mail $LOGNAME
}}}

 * pstree -ap
{{{
  ├─cron,662
  │   └─cron,2647
  │       └─sh,2649 -c /home/mitty/crontest
  │           └─crontest,2650 /home/mitty/crontest
  │               └─sleep,2658 60
}}}

 * mail
{{{
Mail version 8.1.2 01/15/2001.  Type ? for help.
"/var/mail/mitty": 2 messages 2 new
>N  1 mitty@lucid.mitty  Tue May 18 16:30   15/540
 N  2 mitty@lucid.mitty  Tue May 18 16:31   16/595
&
Message 1:
From mitty@lucid.mitty.jp  Tue May 18 16:30:01 2010
X-Original-To: mitty
To: mitty@lucid.mitty.jp
Date: Tue, 18 May 2010 16:30:01 +0900 (JST)
From: mitty@lucid.mitty.jp (mitty)

total 0
-rw-r--r-- 1 mitty mitty  0 May 18 16:30 2650.16:30:01
drwx------ 2 mitty mitty 22 May 18 13:51 ssh-qAiiolp854

&
Message 2:
From mitty@lucid.mitty.jp  Tue May 18 16:31:02 2010
X-Original-To: mitty
To: mitty@lucid.mitty.jp
Date: Tue, 18 May 2010 16:31:01 +0900 (JST)
From: mitty@lucid.mitty.jp (mitty)

total 0
-rw-r--r-- 1 mitty mitty  0 May 18 16:30 2650.16:30:01
-rw-r--r-- 1 mitty mitty  0 May 18 16:31 2650.16:31:01
drwx------ 2 mitty mitty 22 May 18 13:51 ssh-qAiiolp854
}}}



 == バックグラウンド sleep ==
 * /home/mitty/crontest
{{{
#!/bin/sh

export LANG=C


touch /tmp/cron.$$.`date +%T.%N`
ls -l /tmp

sleep 60 &

touch /tmp/cron.$$.`date +%T.%N`
ls -l /tmp
}}}

 * pstree -ap
{{{
  ├─cron,662
  │   └─cron,2948
  │       ├─sendmail,2955 -i -FCronDaemon -oem mitty
  │       │   └─postdrop,2959 -r
  │       └─(sh,2950)

  ├─sleep,2956 60
}}}

 * mail
{{{
Mail version 8.1.2 01/15/2001.  Type ? for help.
"/var/mail/mitty": 1 message 1 new
>N  1 root@lucid.mitty.  Tue May 18 16:53   25/982   Cron <mitty@lucid> /home/mi
&
Message 1:
From mitty@lucid.mitty.jp  Tue May 18 16:53:02 2010
X-Original-To: mitty
From: root@lucid.mitty.jp (Cron Daemon)
To: mitty@lucid.mitty.jp
Subject: Cron <mitty@lucid> /home/mitty/crontest
Content-Type: text/plain; charset=ANSI_X3.4-1968
X-Cron-Env: <SHELL=/bin/sh>
X-Cron-Env: <HOME=/home/mitty>
X-Cron-Env: <PATH=/usr/bin:/bin>
X-Cron-Env: <LOGNAME=mitty>
Date: Tue, 18 May 2010 16:52:02 +0900 (JST)

total 0
-rw-r--r-- 1 mitty mitty  0 May 18 16:52 cron.2951.16:52:01.997709994
drwx------ 2 mitty mitty 22 May 18 13:51 ssh-qAiiolp854
total 0
-rw-r--r-- 1 mitty mitty  0 May 18 16:52 cron.2951.16:52:01.997709994
-rw-r--r-- 1 mitty mitty  0 May 18 16:52 cron.2951.16:52:02.013689211
drwx------ 2 mitty mitty 22 May 18 13:51 ssh-qAiiolp854
}}}

 === with mail command ===
 * /home/mitty/crontest
{{{
#!/bin/sh

export LANG=C


touch /tmp/cron.$$.`date +%T.%N`
ls -l /tmp 2>&1 | mail $LOGNAME

sleep 60 &

touch /tmp/cron.$$.`date +%T.%N`
ls -l /tmp 2>&1 | mail $LOGNAME
}}}

 * pstree -ap
{{{
  ├─cron,662
  │   └─cron,3006
  │       └─(sh,3008)

  ├─sleep,3017 60
}}}

 * mail
{{{
Mail version 8.1.2 01/15/2001.  Type ? for help.
"/var/mail/mitty": 2 messages 2 new
>N  1 mitty@lucid.mitty  Tue May 18 16:56   15/555
 N  2 mitty@lucid.mitty  Tue May 18 16:56   16/625
&
Message 1:
From mitty@lucid.mitty.jp  Tue May 18 16:56:01 2010
X-Original-To: mitty
To: mitty@lucid.mitty.jp
Date: Tue, 18 May 2010 16:56:01 +0900 (JST)
From: mitty@lucid.mitty.jp (mitty)

total 0
-rw-r--r-- 1 mitty mitty  0 May 18 16:56 cron.3009.16:56:01.044354156
drwx------ 2 mitty mitty 22 May 18 13:51 ssh-qAiiolp854

&
Message 2:
From mitty@lucid.mitty.jp  Tue May 18 16:56:01 2010
X-Original-To: mitty
To: mitty@lucid.mitty.jp
Date: Tue, 18 May 2010 16:56:01 +0900 (JST)
From: mitty@lucid.mitty.jp (mitty)

total 0
-rw-r--r-- 1 mitty mitty  0 May 18 16:56 cron.3009.16:56:01.044354156
-rw-r--r-- 1 mitty mitty  0 May 18 16:56 cron.3009.16:56:01.089449007
drwx------ 2 mitty mitty 22 May 18 13:51 ssh-qAiiolp854
}}}

 === >/dev/null 2>&1 & ===
 * /home/mitty/crontest
{{{
#!/bin/sh

export LANG=C


touch /tmp/cron.$$.`date +%T.%N`
ls -l /tmp 2>&1 | mail $LOGNAME

sleep 60 >/dev/null 2>&1 &

touch /tmp/cron.$$.`date +%T.%N`
ls -l /tmp 2>&1 | mail $LOGNAME
}}}

 * pstree -ap
{{{
  ├─cron,662

  ├─sleep,3083 60
}}}

mail
{{{
Mail version 8.1.2 01/15/2001.  Type ? for help.
"/var/mail/mitty": 2 messages 2 new
>N  1 mitty@lucid.mitty  Tue May 18 17:00   15/555
 N  2 mitty@lucid.mitty  Tue May 18 17:00   16/625
&
Message 1:
From mitty@lucid.mitty.jp  Tue May 18 17:00:01 2010
X-Original-To: mitty
To: mitty@lucid.mitty.jp
Date: Tue, 18 May 2010 17:00:01 +0900 (JST)
From: mitty@lucid.mitty.jp (mitty)

total 0
-rw-r--r-- 1 mitty mitty  0 May 18 17:00 cron.3075.17:00:01.108414369
drwx------ 2 mitty mitty 22 May 18 13:51 ssh-qAiiolp854

&
Message 2:
From mitty@lucid.mitty.jp  Tue May 18 17:00:01 2010
X-Original-To: mitty
To: mitty@lucid.mitty.jp
Date: Tue, 18 May 2010 17:00:01 +0900 (JST)
From: mitty@lucid.mitty.jp (mitty)

total 0
-rw-r--r-- 1 mitty mitty  0 May 18 17:00 cron.3075.17:00:01.108414369
-rw-r--r-- 1 mitty mitty  0 May 18 17:00 cron.3075.17:00:01.161439061
drwx------ 2 mitty mitty 22 May 18 13:51 ssh-qAiiolp854
}}}

 = 環境変数 =
 * crontab -l
{{{
* * * * * /home/mitty/test
}}}
 * cat /home/mitty/test
{{{
#!/bin/sh

export
}}}

 == Ubuntu lucid ==
{{{
export HOME='/home/mitty'
export LOGNAME='mitty'
export PATH='/usr/bin:/bin'
export PWD='/home/mitty'
export SHELL='/bin/sh'
}}}