{"title":"Bash\u30b9\u30af\u30ea\u30d7\u30c8\u3067\u5909\u6570\u306b\u521d\u671f\u5024\u3092\u3076\u3063\u8fbc\u3080","image_url":null,"type":"rich","provider_url":"https://hatena.blog","provider_name":"Hatena Blog","published":"2014-03-15 23:50:10","width":"100%","author_url":"https://blog.hatena.ne.jp/shuzo_kino/","blog_title":"Bye Bye Moore","url":"https://shuzo-kino.hateblo.jp/entry/2014/03/15/235010","version":"1.0","description":"\u7a7a\u306e\u5909\u6570\u306b\u5024\u3092\u30bb\u30c3\u30c8\u3059\u308b\u5834\u5408... -bash$ echo $VAL_A -bash$ echo ${VAL_A:-100} 100\u3053\u3093\u306a\u611f\u3058\u3067\u6307\u5b9a\u3057\u305f\u521d\u671f\u5024\u304c\u5165\u308a\u307e\u3059\u3002 -bash$ VAL_A=200 -bash$ echo ${VAL_A:-100} 200\u3059\u3067\u306b\u5024\u304c\u683c\u7d0d\u3055\u308c\u3066\u3044\u308b\u5834\u5408\u3001 \u4ee3\u5165\u3055\u308c\u307e\u305b\u3093\u3002\u304a\u307e\u3051\uff1a\u5909\u6570\u3092\u89e3\u6cd5\u3057\u305f\u3044\u5834\u5408 unset\u3068\u3044\u3046\u5974\u3067\u3067\u304d\u307e\u3059\u3002 builtin\u306e\u4e00\u3064\u306a\u306e\u3067\u3001sh\u74b0\u5883\u3067\u4f7f\u3048\u307e\u3059\u3002 -bash$ unset VAL_A -bash$ echo $VAL_A","author_name":"shuzo_kino","categories":["unix"],"height":"190","blog_url":"https://shuzo-kino.hateblo.jp/","html":"<iframe src=\"https://hatenablog-parts.com/embed?url=https%3A%2F%2Fshuzo-kino.hateblo.jp%2Fentry%2F2014%2F03%2F15%2F235010\" title=\"Bash\u30b9\u30af\u30ea\u30d7\u30c8\u3067\u5909\u6570\u306b\u521d\u671f\u5024\u3092\u3076\u3063\u8fbc\u3080 - Bye Bye Moore\" class=\"embed-card embed-blogcard\" scrolling=\"no\" frameborder=\"0\" style=\"display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;\"></iframe>"}