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kiyo_hiko 2019/05/27
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kiyo_hiko 2019/04/24
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kiyo_hiko 2019/04/24
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kiyo_hiko 2017/10/10
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kiyo_hiko 2017/05/15
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kiyo_hiko 2015/08/12
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nullpo

asp

dotnet

null

trouble

model

view
ãƒªãƒ³ã‚¯
ASP.NET MVC datetime culture issue when passing value back to controller
kiyo_hiko 2015/08/11
è‹¥å¹²é•ã†ã‘ã©ã€"ï¼ Html.EditorFor(m => m.Date, "yyyyå¹´Mæœˆdæ—¥ï¼ˆdddï¼‰", new { htmlAttr..." ãŒãƒ¢ãƒ‡ãƒ«ã«ãƒã‚¤ãƒ³ãƒ‰ã™ã‚‹ã¨ãã«ParseExactçš„ãªäº‹ã•ã‚Œãšnullã«è©•ä¾¡ã•ã‚Œã‚‹ç¾è±¡ã‚’ã‚°ã‚°ã£ãŸã‚‰æ¥ãŸã€‚ãªãŠ"yyyyå¹´Mæœˆdæ—¥ (ddd)"ã«å¤‰ãˆãŸã‚‰è§£æ±ºã—ãŸã€‚

asp

dotnet

mvc

datetime

null

problem
ãƒªãƒ³ã‚¯
Javaã«ãŠã‘ã‚‹nullã€‚ã“ã‚Œã¾ã§ã¨ã“ã‚Œã‹ã‚‰
ã“ã®ãƒ–ãƒ©ã‚¦ã‚¶ ãƒãƒ¼ã‚¸ãƒ§ãƒ³ã®ã‚µãƒãƒ¼ãƒˆã¯çµ‚äº†ã—ã¾ã—ãŸã€‚ã‚µãƒãƒ¼ãƒˆã•ã‚Œã¦ã„ã‚‹ãƒ–ãƒ©ã‚¦ã‚¶ã«ã‚¢ãƒƒãƒ—ã‚°ãƒ¬ãƒ¼ãƒ‰ã—ã¦ãã ã•ã„ã€‚
kiyo_hiko 2015/04/12
NonNullã¨ã„ã†ã‚¢ãƒŽãƒ†ãƒ¼ã‚·ãƒ§ãƒ³

java

tips

null
ãƒªãƒ³ã‚¯
Nullã¨Emptyã¨Nothingã¨ç©ºã®æ–‡å—åˆ—ã®é•ã„ï¼šAccess VBAï½œå³åŠ¹ãƒ†ã‚¯ãƒ‹ãƒƒã‚¯ï½œExcel VBAã‚’å¦ã¶ãªã‚‰moug
Nullã¨Emptyã¨Nothingã¨ç©ºã®æ–‡å—åˆ—ã®é•ã„ (Access 97/2000/2002/2003/2007/2010) ãƒ„ã‚¤ãƒ¼ãƒˆ VBAã§ã¯å¤‰æ•°ã‚„ãƒ•ã‚£ãƒ¼ãƒ«ãƒ‰ã«æœ‰åŠ¹ãªå€¤ãŒãªã„çŠ¶æ…‹ã‚„ã€ç©ºã®çŠ¶æ…‹ã‚’è¡¨ã™å€¤ãŒã„ãã¤ã‚‚ã‚ã‚Šã¾ã™ã€‚ ã“ã“ã§ã¯ã€ãã‚Œãžã‚Œã®æ„å‘³ã‚„ä½¿ç”¨ä¸Šã®æ³¨æ„ã«ã¤ã„ã¦ã”ç´¹ä»‹ã—ã¾ã™ã€‚ â– é•·ã•0ã®æ–‡å—åˆ—ï¼ˆ""ï¼‰ æ–‡å—ã‚’1ã¤ã‚‚å«ã¾ãªã„æ–‡å—åˆ— ("") ã§ã™ã€‚ ã€Œé•·ã•0ã®æ–‡å—åˆ—ã€ã®åå‰ã®ã¨ãŠã‚Šã€Lené–¢æ•°ã‚„LenBé–¢æ•°ã®å¼•æ•°ã«æŒ‡å®šã™ã‚‹ã¨0ã‚’è¿”ã—ã¾ã™ã€‚ Dim myStr As String myStr = "" Debug.Print Len(myStr) '--> 0ã€€ã¨è¡¨ç¤ºã•ã‚Œã‚‹ â– å€¤0ã®æ–‡å—åˆ—ï¼ˆvbNullStringï¼‰ Stringåž‹ã®å¤‰æ•°ã®åˆæœŸçŠ¶æ…‹ã‚’è¡¨ã™å€¤ã§ã™ã€‚vbNullStringã¨ã„ã†å®šæ•°ã§è¡¨ã—ã¾ã™ã€‚ é•·ã•0ã®æ–‡å—åˆ—ï¼ˆ""ï¼‰ã¨åŒæ§˜ã«ã€Len/LenBé–¢æ•°ã®å¼•æ•°ã«æŒ‡å®šã™ã‚‹ã¨ 0
kiyo_hiko 2014/09/10
Emptyâ€¦Nullâ€¦Nothingâ€¦ ã©ã“ã‹ã‚‰æ¥ã¦ ã©ã“ã¸è¡Œãï¼Ÿ ãã‚“ãªã‚‚ã®ã¯â€¦

vba

null

nil

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ãƒªãƒ³ã‚¯
Swiftã“ã¨ã¯ã˜ã‚ï¼šString?ã®ã‚¯ã‚¨ã‚¹ãƒãƒ§ãƒ³ãƒžãƒ¼ã‚¯ã£ã¦ä½•ï¼Ÿ - Shoichi Matsuda's diary
Swiftå‡ºã¾ã—ãŸãï¼ WWDCã§çªç„¶ã®è¨€èªžç™ºè¡¨ã§é©šãã§ã™ã€‚ ç„¡æ–™ã®ãƒ‰ã‚ãƒ¥ãƒ¡ãƒ³ãƒˆãŒæä¾›ã•ã‚Œã¦ãŠã‚Šã€ã–ã£ã¨èªã‚“ã§ã¿ãŸé™ã‚Šæœ€è¿‘ã®è¨€èªžã®ã‚¨ãƒƒã‚»ãƒ³ã‚¹ã‚’è‰²ã€…ã¨å–ã‚Šè¾¼ã‚“ã è‰¯ã„æ„å‘³ã§ç‰¹å¾´ã®ãªã„ï¼ˆã‹ãªã‚Šæ›¸ãã‚„ã™ãã†ãªï¼ï¼‰è¨€èªžã¨ã„ã†å°è±¡ã‚’å—ã‘ã¾ã—ãŸã€‚ ä»Šå›žã¯ãã‚“ãªSwiftã®ä¸ã®optional valueãªã©ã¨å‘¼ã°ã‚Œã¦ã„ã‚‹è¨€èªžä»•æ§˜ã«ã¤ã„ã¦å–ã‚Šä¸Šã’ã¦ã„ãã¾ã™ã€‚ ã©ã‚Œã®ã“ã¨ï¼Ÿ ãƒ‰ã‚ãƒ¥ãƒ¡ãƒ³ãƒˆä¸ã«å‡ºã¦ãã‚‹ä»¥ä¸‹ã®æ§˜ãªè¨˜è¿°ã§ã™ã€‚ var optionalString: String? = "hello" optionalString = nil println(optionalString) ã“ã®String?ã€ãªã‚“ã®ã“ã¨ã ã‹ã‚ã‹ã‚Šã¾ã™ã‹ï¼Ÿ ã“ã®ã‚¯ã‚¨ã‚¹ãƒãƒ§ãƒ³ãƒžãƒ¼ã‚¯ã€ã©ã†ã‚„ã£ã¦ä½¿ã†ã®ï¼Ÿ ä½¿ã„æ–¹ã‚’è¦‹ã¦ã„ãã¾ã—ã‚‡ã†ã€‚ ã¾ãšæ™®é€šã®å¤‰æ•°å®£è¨€ã§ä»¥ä¸‹ã®æ§˜ã«æ›¸ã„ã¦ã¿ã¾ã—ã‚‡ã†ã€‚ var normalString = "aaa" nor
kiyo_hiko 2014/06/04
nullable, maybeçš„ãª

ï¼Ÿ

swift

null
ãƒªãƒ³ã‚¯
NULLã¨ãƒ–ãƒ©ãƒ³ã‚¯ã®é•ã„ - OKWAVE
â˜…ç§ã«ã¯ã€Ž""ï¼ãƒ–ãƒ©ãƒ³ã‚¯ã€ã®è¡¨ç¾ãŒã—ã£ãã‚Šæ¥ã¾ã›ã‚“ã€‚ ãƒ»ã€Žblankã€ã£ã¦ã®ã¯ã€ç©ºç™½ã€ä½™ç™½ã€ã‚¹ãƒšãƒ¼ã‚¹ã¨ã„ã†æ„å‘³ã§ã™ã€‚ ãªã®ã§ã€Ž""ã€ã‚’ãƒ–ãƒ©ãƒ³ã‚¯ã¨å‘¼ã¶è¡¨ç¾ã¯ãŠã‹ã—ã„ã¨æ€ã„ã¾ã™ã€‚æ™®é€šã¯ã€Ž""ã€ã‚’ç©ºæ–‡å—åˆ—ã¨å‘¼ã³ã¾ã™ã€‚ ç©ºæ–‡å—åˆ—ã¨ã¯ã€æ–‡å—åˆ—ãŒä½•ã‚‚ãªã„ãŒæ–‡å—åˆ—ã¨ã—ã¦ã®ãƒã‚¤ãƒ³ã‚¿(ã‚¢ãƒ‰ãƒ¬ã‚¹)ã‚’æŒã¤ãƒ‡ãƒ¼ã‚¿ã§ã™ã€‚ ãƒ»ãã—ã¦ã€NULL ã¯ãƒã‚¤ãƒ³ã‚¿(ã‚¢ãƒ‰ãƒ¬ã‚¹)ã®å€¤ãŒã‚¼ãƒã‚’æŒã¡ã€ãƒã‚¤ãƒ³ã‚¿ã«ã¯ãƒ‡ãƒ¼ã‚¿ã¯å‰²ã‚Šä»˜ã‘ã¦ã„ãªã„äº‹ã‚’ æ„å‘³ã—ã¾ã™ã€‚ã¤ã¾ã‚Šã€Žãƒ‡ãƒ¼ã‚¿ãªã—ã€ã‚’æ„å‘³ã—ã¾ã™ã€‚ ãƒ»ä»–ã«ã‚‚ NULL ã«ã¯ã„ã‚ã„ã‚ãªæ„å‘³ã‚’æŒãŸã›ãŸã‚Šã—ã¾ã™ã€‚ (1)æ¤œç´¢å‡¦ç†ã§æ–‡å—ã€æ–‡å—ç¾¤ã€æ–‡å—åˆ—ãªã©ãŒè¦‹ã¤ã‹ã‚‰ãªã„ã¨ NULL ã‚’è¿”ã™ã€‚â†’ã‚¨ãƒ©ãƒ¼ã®æ„å‘³ã€‚ (2)æœ€åˆã€ãƒã‚¤ãƒ³ã‚¿(ã‚¢ãƒ‰ãƒ¬ã‚¹)ã®å¤‰æ•°ã« NULL ã‚’ã‚»ãƒƒãƒˆã—ã¦åˆæœŸåŒ–ã—ã¦ãŠãã€‚â†’åˆæœŸåŒ–ã®æ„å‘³ã€‚ (3)Cè¨€èªžã®ã€Žfgetsã€é–¢æ•°ãªã©ã¯ã€ãƒ•ã‚¡ã‚¤ãƒ«ã®çµ‚ã‚ã‚Šã‹ã€ã‚¨ãƒ©ãƒ¼ãŒç™ºç”Ÿã™ã‚‹ã¨ NULL ã‚’è¿”ã—ã¦ãŠ
kiyo_hiko 2014/01/23
ãƒŠãƒ«ã¯ä»¥å‰SQL([asin:4798115169])ã§å‹‰å¼·ã—ãŸ â†’ http://codezine.jp/article/detail/532

logic

null
ãƒªãƒ³ã‚¯
String.valueOfã®ç½ : ã¸ã£ã½ã“SEã®ãƒ¡ãƒ¢ãƒ¡ãƒ¢
ã‚³ãƒ³ãƒ”ãƒ¥ãƒ¼ã‚¿ãŒè‹¦æ‰‹ãªSEãŒæ—¥ã€…è¨˜ã™ãƒ¡ãƒ¢ã§ã™ã€‚ ã„ã¤ã‹èª°ã‹ã®ãŠå½¹ã«ç«‹ã¦ã‚Œã°å¹¸ã„ã§ã™ã€‚ â€»ã“ã®ãƒ–ãƒã‚°è¨˜è¼‰ã®å†…å®¹ã‚’ã”åˆ©ç”¨ã«ãªã‚‹å ´åˆã¯ã€è‡ªå·±è²¬ä»»ã§ãŠé¡˜ã„ã—ã¾ã™ã€‚ä½•ãŒèµ·ã“ã£ã¦ã‚‚ä¸€åˆ‡è²¬ä»»ã¯æŒã¦ã¾ã›ã‚“m(__)m String#valueOf(Object obj)ã£ã¦ã€nullãŒå…¥ã‚Œã°NullPointerExceptionã§ã‚‚æŠ•ã’ã¦ãã‚Œã‚‹ã‚‚ã®ã ã¨æ€ã£ã¦ã„ã¾ã—ãŸã€‚ çµæžœï¼š String value = String.valueOf(null) System.out.println(value) -> ã€Œnullã€ã¨å‡ºåŠ›ã•ã‚Œã‚‹ System.out.println(value.length()) -> ã€Œ4ã€ã¨å‡ºåŠ›ã•ã‚Œã‚‹ String.valueOfã«nullã‚’å…¥ã‚Œã‚‹ã¨ã€æ–‡å—åˆ—"null"æ‰±ã„ã«ãªã‚‹ã¨ã¯â€¦ ç¢ºã‹ã«JavaDocã«ä»¥ä¸‹ã®ã‚ˆã†ãªè¨˜è¿°ãŒã€‚ ***************************
kiyo_hiko 2014/01/04
ãƒŠãƒ«ã¯"null"ã«ãªã‚‹

java

string

tips

null
ãƒªãƒ³ã‚¯
ã€ç”»åƒã‚ã‚Šã€‘åå¤å±‹å¸‚ãŒå¸‚æ°‘ã«é€ã£ãŸãƒ¡ãƒ¼ãƒ«ãŒæ„å‘³ä¸æ˜Žã™ãŽã‚‹ï½—ï½—ï½—ï½—ï½—ï½—ï½—ï½—ï½—ï½—ï½— : æš‡äººï¼¼(^o^)ï¼é€Ÿå ±
ã€ç”»åƒã‚ã‚Šã€‘åå¤å±‹å¸‚ãŒå¸‚æ°‘ã«é€ã£ãŸãƒ¡ãƒ¼ãƒ«ãŒæ„å‘³ä¸æ˜Žã™ãŽã‚‹ï½—ï½—ï½—ï½—ï½—ï½—ï½—ï½—ï½—ï½—ï½— Tweet 1ï¼š ãƒ•ãƒ©ãƒ³ã‚±ãƒ³ã‚·ãƒ¥ã‚¿ã‚¤ãƒŠãƒ¼(å²¡å±±çœŒ)ï¼š2013/09/05(æœ¨) 18:31:57.23 ID:Nu5SMiDU0 åå¤å±‹å¸‚ã€è±ªé›¨æƒ…å ±ãƒ¡ãƒ¼ãƒ«èª¤é…ä¿¡ åå¤å±‹å¸‚ãŒï¼”æ—¥å¤œã€è±ªé›¨ã«é–¢ã™ã‚‹ç·Šæ€¥æƒ…å ±ã‚’æºå¸¯é›»è©±ã«ä¼ãˆã‚‹ãƒ¡ãƒ¼ãƒ«ã§èª¤é€ä¿¡ã‚’ã—ãŸã€‚ åˆå¾Œï¼™æ™‚åŠã”ã‚ã€Œï½Žï½•ï½Œï½Œã€€ï½Žï½•ï½Œï½Œã€€ï¼ˆåå¤å±‹å¸‚ï¼‰ã€ã¨ã„ã†æ„å‘³ä¸æ˜Žã®ãƒ¡ãƒ¼ãƒ«ã‚’é…ä¿¡ã€‚å¸‚ç½å®³å¯¾ç–æœ¬éƒ¨ã«ã‚ˆã‚‹ã¨ã€ æœ¬æ¥ã¯ã€Œé¿é›£å‹§å‘Šã‚„é¿é›£æº–å‚™æƒ…å ±ã®è§£é™¤ã€ã¨ã„ã£ãŸå†…å®¹ãŒé€ã‚‰ã‚Œã‚‹ã¯ãšã ã£ãŸã€‚ é…ä¿¡å¾Œã«å•ã„åˆã‚ã›ã®é›»è©±ãŒåæ•°ä»¶ã‚ã£ãŸã€‚ç´„ï¼’ï¼åˆ†å¾Œã«åˆ¥ã®ãƒ‘ã‚½ã‚³ãƒ³ã§é€ä¿¡ã™ã‚‹ã¨ã€æœ¬æ¥ã®å†…å®¹ã§ é…ä¿¡ã•ã‚ŒãŸã€‚ãƒ¡ãƒ¼ãƒ«ã®æ–‡é¢ã¯æ‹…å½“è€…ãŒãƒ‘ã‚½ã‚³ãƒ³ã«æ‰‹æ‰“ã¡ã§å…¥åŠ›ã™ã‚‹ä»•çµ„ã¿ã ãŒå…¥åŠ›ãƒŸã‚¹ã¯ãªã‹ã£ãŸã¨ã„ã„ã€ èª¤é€ä¿¡ã®åŽŸå› ã‚’èª¿ã¹ã¦ã„ã‚‹ã€‚ http://www.asahi.com/national/update/090
kiyo_hiko 2013/09/08
ãƒŠãƒ«ã ã£ãŸã‚‰é€ã‚‰ãªã„ã‚ˆã†ã«ã—ãªã„ã¨

null
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é€£è¼‰: IBM Watson Workspace #é¬¼ã‚ã‹ ã‚¢ãƒ—ãƒªã‚±ãƒ¼ã‚·ãƒ§ãƒ³é–‹ç™º: ç¬¬ 7 å›ž: IBM Watson Workspace ã§ AI ã‚’åˆ©ç”¨ã—ãŸã‚¢ãƒ—ãƒªé€£æºã®å®Ÿç¾ #é¬¼ã‚ã‹ è§£èª¬ï¼ˆå‰ç·¨ï¼‰
IBM Developer is your one-stop location for getting hands-on training and learning in-demand skills on relevant techno logies such as generative AI, data science, AI, and open source.
kiyo_hiko 2013/08/16
HotSpotVMã®å°Žå…¥ã¯Java1.2ã‹ã‚‰ã€‚å˜ç™ºã®å°ã•ã„ã‚ªãƒ–ã‚¸ã‚§ã‚¯ãƒˆã®å®£è¨€ã«ç¥žçµŒè³ªã«ãªã‚‹å¿…è¦ã¯ãªã„ // ã‚¨ã‚¹ã‚±ãƒ¼ãƒ—è§£æžã¨ã„ã†æŠ€ã‚‚ã‚ã‚Šã€ã‚ªãƒ–ã‚¸ã‚§ã‚¯ãƒˆã¯é€Ÿæ”»ã§æ¶ˆã•ã‚Œã‚‹ // é™½ã«nullã‚’ä»£å…¥ã™ã‚‹ã¨ã‚ªãƒ–ã‚¸ã‚§ã‚¯ãƒˆæµ®éŠã‚’å¼•ãèµ·ã“ã™ã“ã¨ãŒã‚ã‚‹

java

mem

heap

gc

null

jvm
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Coding: Maybe vs Null Object patterns | Mark Needham
On the project Iâ€™m currently working on my colleague Christian Blunden has introduced a version of the Maybe type into the code base, a concept that originally derives from the world of functional programming. The code looks a bit like this: public interface Maybe<T> { bool HasValue(); T Value(); } public class Some<T> : Maybe<T> { private readonly T t; public Some(T t) { this.t = t; } public bool
kiyo_hiko 2012/11/27
ã€Œreadonly T tã€ã«nullã‚’å…¥ã‚Œã‚‹ã®ã‚’é¿ã‘ã¦åˆ¥ã‚¯ãƒ©ã‚¹Noneã«ã—ã¦ã‚‹ç†ç”±ãŒã„ã¾ã„ã¡ç†è§£ã§ãã¦ãªã„

cpp

ã†ã†ã‚€

maybe

null
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/dev/null - Wikipedia
/dev/nullï¼ˆnullãƒ‡ãƒã‚¤ã‚¹ã¨ã‚‚å‘¼ã°ã‚Œã‚‹ï¼‰ã¯ã€UNIXã‚„Unixç³»ã‚ªãƒšãƒ¬ãƒ¼ãƒ†ã‚£ãƒ³ã‚°ã‚·ã‚¹ãƒ†ãƒ (OS) ã«ãŠã‘ã‚‹ã‚¹ãƒšã‚·ãƒ£ãƒ«ãƒ•ã‚¡ã‚¤ãƒ«ã®1ã¤ã§ã€ãã“ã«æ›¸ãè¾¼ã¾ã‚ŒãŸãƒ‡ãƒ¼ã‚¿ã‚’å…¨ã¦æ¨ã¦ï¼ˆwriteã‚·ã‚¹ãƒ†ãƒ ã‚³ãƒ¼ãƒ«ã¯æˆåŠŸã™ã‚‹ï¼‰ã€èªã¿å‡ºã—ã¦ã‚‚ã©ã‚“ãªãƒ—ãƒã‚»ã‚¹ã«å¯¾ã—ã¦ã‚‚ãƒ‡ãƒ¼ã‚¿ã‚’è¿”ã•ãªã„ï¼ˆEOFã‚’è¿”ã™ï¼‰ã€‚ /dev/null ã¯é€šå¸¸ã€ãƒ—ãƒã‚»ã‚¹ã®ä¸è¦ãªå‡ºåŠ›ã‚¹ãƒˆãƒªãƒ¼ãƒ ã‚’æ¨ã¦ã‚‹ã®ã«ä½¿ã†ã‹ã€å…¥åŠ›ã‚¹ãƒˆãƒªãƒ¼ãƒ ã®ãŸã‚ã®ç©ºã®ãƒ•ã‚¡ã‚¤ãƒ«ã¨ã—ã¦ä½¿ã†ã€‚ã“ã‚Œã¯ä¸€èˆ¬ã«ãƒªãƒ€ã‚¤ãƒ¬ã‚¯ãƒˆã«ã‚ˆã£ã¦ãªã•ã‚Œã‚‹ã€‚ãƒ—ãƒã‚°ãƒ©ãƒžã€ç‰¹ã«Unixç³»ã®ãƒ—ãƒã‚°ãƒ©ãƒžã®é–“ã§ã¯ã€ãƒ“ãƒƒãƒˆãƒã‚±ãƒ„ (bit bucket)ã€ã‚ã‚‹ã„ã¯ãƒ–ãƒ©ãƒƒã‚¯ãƒ›ãƒ¼ãƒ« (black hole) ãªã©ã¨ã‚‚å‘¼ã°ã‚Œã‚‹ã€‚ UNIXã‚„Unixç³»OSã®ã‚½ãƒ•ãƒˆã‚¦ã‚§ã‚¢ã¯ã€å‹•ä½œæ™‚ã«æ¨™æº–å‡ºåŠ›ã‚„æ¨™æº–ã‚¨ãƒ©ãƒ¼å‡ºåŠ›ã«å‹•ä½œçŠ¶æ³ã‚„ã€ã‚¨ãƒ©ãƒ¼ã‚„è¦å‘Šã‚’ä¼ãˆã‚‹ãƒ¡ãƒƒã‚»ãƒ¼ã‚¸ã‚’å‡ºåŠ›ã™ã‚‹ã“ã¨ãŒã‚ã‚‹ã€‚ã“ã‚Œã‚‰ã¯ãƒ‡ãƒ•ã‚©ãƒ«ãƒˆã§ç”»é¢ã«è¡¨ç¤ºã•ã‚Œã€cron
kiyo_hiko 2012/08/17
ã€Œbit bucketã€ã¨ã‚‚ã„ã†ã‚‰ã—ã„ã€‚æŸã‚µãƒ¼ãƒ“ã‚¹ã¿ãŸã„ãªåå‰

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console

cmd

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