{"id":1181,"date":"2020-01-17T16:41:27","date_gmt":"2020-01-17T16:41:27","guid":{"rendered":"https:\/\/golangbyexamples.com\/?p=1181"},"modified":"2020-01-17T16:41:31","modified_gmt":"2020-01-17T16:41:31","slug":"append-file-golang","status":"publish","type":"post","link":"https:\/\/golangbyexamples.com\/append-file-golang\/","title":{"rendered":"Append to an existing file in Go (Golang)"},"content":{"rendered":"\n<p class=\"has-medium-font-size\"><strong>os.OpenFile()<\/strong> function of the os package can be used to open to a file in an append mode and then write to it<\/p>\n\n\n\n<p class=\"has-medium-font-size\">Let&#8217;s see an example. In the below program:<\/p>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\"><li>First, write to a file using <strong>ioutil<\/strong> package<\/li><li>Open the file again in Append mode and write the second line to it<\/li><li>Read the file to verify the content.<\/li><\/ul>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\n\nimport (\n    \"fmt\"\n    \"io\/ioutil\"\n    \"log\"\n    \"os\"\n)\n\nfunc main() {\n    \/\/Write first line\n    err := ioutil.WriteFile(\"temp.txt\", []byte(\"first line\\n\"), 0644)\n    if err != nil {\n        log.Fatal(err)\n    }\n    \n    \/\/Append second line\n    file, err := os.OpenFile(\"temp.txt\", os.O_APPEND|os.O_WRONLY, 0644)\n    if err != nil {\n        log.Println(err)\n    }\n    defer file.Close()\n    if _, err := file.WriteString(\"second line\"); err != nil {\n        log.Fatal(err)\n    }\n    \n    \/\/Print the contents of the file\n    data, err := ioutil.ReadFile(\"temp.txt\")\n    if err != nil {\n        log.Fatal(err)\n    }\n    fmt.Println(string(data))\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Output:<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">first line\nsecond line<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"<p>os.OpenFile() function of the os package can be used to open to a file in an append mode and then write to it Let&#8217;s see an example. In the below program: First,&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"spay_email":"","footnotes":"","jetpack_publicize_message":"","jetpack_is_tweetstorm":false},"categories":[1],"tags":[38,3],"class_list":["post-1181","post","type-post","status-publish","format-standard","hentry","category-tech","tag-file","tag-go"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v22.7 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Append to an existing file in Go (Golang) - Welcome To Golang By Example<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/golangbyexamples.com\/append-file-golang\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Append to an existing file in Go (Golang) - Welcome To Golang By Example\" \/>\n<meta property=\"og:description\" content=\"os.OpenFile() function of the os package can be used to open to a file in an append mode and then write to it Let&#8217;s see an example. 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