{"id":278,"date":"2026-10-13T07:41:13","date_gmt":"2026-10-13T07:41:13","guid":{"rendered":"http:\/\/www.scmgalaxy.com\/tutorials\/2010\/07\/22\/how-to-put-comment-in-ant-comments-in-apache-ant\/"},"modified":"2026-10-13T07:41:13","modified_gmt":"2026-10-13T07:41:13","slug":"how-to-put-comment-in-ant-comments-in-apache-ant","status":"publish","type":"post","link":"https:\/\/www.devopsschool.com\/blog\/how-to-put-comment-in-ant-comments-in-apache-ant\/","title":{"rendered":"Apache Ant Comments and echo Task: Write Clear build.xml Files and Control Log Output"},"content":{"rendered":"\n

Originally published on 2010-07-22; fully revised and updated.<\/em><\/p>\n\n\n\n

If you maintain Ant build files, comments and logging are essential for readability and troubleshooting. This guide explains how to use XML comments in build.xml<\/code>, how the echo<\/code> task behaves at different log levels, and how to choose the right approach for documentation versus runtime diagnostics.<\/p>\n\n\n

\n
\"comments-in-apache-ant\"<\/figure>\n<\/div>\n\n\n

Commenting in Ant build files (build.xml)<\/h2>\n\n\n\n

Ant build files are XML, so comments use standard XML comment syntax: <!-- ... --><\/code>. These comments are for humans reading the file and are not shown during normal build output.<\/p>\n\n\n

<?xml version=\"1.0\" encoding=\"UTF-8\"?><\/span>\n<project<\/span> name<\/span>=\"demo\"<\/span> default<\/span>=\"compile\"<\/span>><\/span>\n    <!-- Compile Java sources into build\/classes --><\/span>\n    <target<\/span> name<\/span>=\"compile\"<\/span>><\/span>\n        <javac<\/span> srcdir<\/span>=\"src\"<\/span> destdir<\/span>=\"build\/classes\"<\/span>\/><\/span>\n    <\/target<\/span>><\/span>\n<\/project<\/span>><\/span><\/code><\/span>Code language:<\/span> HTML, XML<\/span> (<\/span>xml<\/span>)<\/span><\/small><\/pre>\n\n\n
Keep comments short and intention-focused (why a target exists, assumptions, non-obvious behavior). As with XML generally, avoid malformed comment syntax and avoid nesting comments.<\/p>\n\n\n\n
XML comments vs echo messages: choose the right mechanism<\/h2>\n\n\n\n
Mechanism<\/th>Purpose<\/th>Visible during build run<\/th>Best for<\/th>Caveats<\/th><\/tr><\/thead>
XML comment (<!– … –>)<\/td>Inline documentation in build.xml<\/td>No<\/td>Design notes, rationale, maintainer guidance<\/td>Not available in runtime logs<\/td><\/tr>
<echo …\/> to console<\/td>Runtime logging<\/td>Yes, depending on level<\/code> and Ant log mode<\/td>Status updates, warnings, debug traces<\/td>Can create noisy logs if overused<\/td><\/tr>
<echo file="…"\/><\/td>Write text to a file<\/td>Writes to file output<\/td>Generating scripts\/config snippets<\/td>When writing to file, log level<\/code> filtering is not the primary behavior<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
Using the echo task effectively<\/h2>\n\n\n\n
The Ant echo<\/code> task writes messages to Ant loggers\/listeners (typically console output unless logging is redirected). You can pass text with the message<\/code> attribute or as nested text, and you can also write output to a file.<\/p>\n\n\n\n
Key echo attributes<\/h3>\n\n\n\n
Attribute<\/th>Description<\/th>Required<\/th>Notes<\/th><\/tr><\/thead>
message<\/td>Message to echo<\/td>No<\/td>Can also be provided as nested text; without message\/text, emits a blank line<\/td><\/tr>
file<\/td>Output file path<\/td>No<\/td>Writes message content to file<\/td><\/tr>
append<\/td>Append to existing file or overwrite<\/td>No<\/td>Default is false; related behavior aligns with Java file writing semantics in FileWriter<\/a><\/td><\/tr>
level<\/td>Log severity filter: error, warning, info, verbose, debug<\/td>No<\/td>Default shown in source material: warning<\/td><\/tr>
encoding<\/td>Encoding for file output<\/td>No<\/td>Source material notes availability since Ant 1.7<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
Common echo styles<\/h3>\n\n\n
<echo<\/span> message=\"Hello, world\"<\/span>\/>\n\n<echo<\/span> message=\"Embed a line break:${line.separator}\"<\/span>\/>\n\n<echo<\/span>>This is a longer message\nacross multiple lines.<\/echo<\/span>>\n\n<echo<\/span> message=\"Deleting drive C:\"<\/span> level=\"debug\"<\/span>\/>\n\n<echo<\/span> level=\"error\"<\/span>>\nImminent failure in the antimatter containment facility.\nPlease withdraw to a safe location.\n<\/echo<\/span>>\n\n<echo<\/span> file=\"runner.csh\"<\/span> append=\"false\"<\/span>>#!\/bin\/tcsh<\/span>\njava -mx1024m ${project.entrypoint} $$*\n<\/echo<\/span>><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
How Ant decides whether an echo message is shown<\/h2>\n\n\n\n
Console visibility depends on both the echo<\/code> level and how Ant is started (-q<\/code>, default, -v<\/code>, -d<\/code>). Higher-verbosity modes show more messages.<\/p>\n\n\n\n
\nflowchart TD\n    A[Ant runs target] --> B[Echo task executes]\n    B --> C{File attribute set}\n    C -- yes --> D[Write message to file]\n    C -- no --> E{Current log mode allows this level}\n    E -- yes --> F[Show in console output]\n    E -- no --> G[Suppress from console]\n<\/pre>\n\n\n\n
Echo statement<\/th>-quiet (-q)<\/th>Default run (no flag)<\/th>-verbose (-v)<\/th>-debug (-d)<\/th><\/tr><\/thead>
<echo message="This is error message." level="error" \/><\/td>ok<\/td>ok<\/td>ok<\/td>ok<\/td><\/tr>
<echo message="This is warning message." \/><\/td>ok<\/td>ok<\/td>ok<\/td>ok<\/td><\/tr>
<echo message="This is info message." level="info" \/><\/td>not logged<\/td>ok<\/td>ok<\/td>ok<\/td><\/tr>
<echo message="This is verbose message." level="verbose" \/><\/td>not logged<\/td>not logged<\/td>ok<\/td>ok<\/td><\/tr>
<echo message="This is debug message." level="debug" \/><\/td>not logged<\/td>not logged<\/td>not logged<\/td>ok<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n
ant -q\nant\nant -v\nant -d<\/code><\/span><\/pre>\n\n\n
Practical build.xml example: comments plus actionable logging<\/h2>\n\n\n
<project<\/span> name<\/span>=\"sample-app\"<\/span> default<\/span>=\"package\"<\/span>><\/span>\n\n    <!-- Central output directory used by all targets --><\/span>\n    <property<\/span> name<\/span>=\"build.dir\"<\/span> value<\/span>=\"build\"<\/span>\/><\/span>\n\n    <target<\/span> name<\/span>=\"clean\"<\/span>><\/span>\n        <echo<\/span> level<\/span>=\"info\"<\/span> message<\/span>=\"Cleaning ${build.dir}\"<\/span>\/><\/span>\n        <delete<\/span> dir<\/span>=\"${build.dir}\"<\/span>\/><\/span>\n    <\/target<\/span>><\/span>\n\n    <target<\/span> name<\/span>=\"package\"<\/span> depends<\/span>=\"clean\"<\/span>><\/span>\n        <!-- This warning is important for operators in standard runs --><\/span>\n        <echo<\/span> level<\/span>=\"warning\"<\/span> message<\/span>=\"Packaging started\"<\/span>\/><\/span>\n\n        <mkdir<\/span> dir<\/span>=\"${build.dir}\"<\/span>\/><\/span>\n\n        <echo<\/span> file<\/span>=\"${build.dir}\/build-meta.txt\"<\/span> append<\/span>=\"false\"<\/span>><\/span>\nproject=sample-app\nbuild.timestamp=${DSTAMP}-${TSTAMP}\n        <\/echo<\/span>><\/span>\n\n        <echo<\/span> level<\/span>=\"debug\"<\/span> message<\/span>=\"Wrote ${build.dir}\/build-meta.txt\"<\/span>\/><\/span>\n    <\/target<\/span>><\/span>\n\n<\/project<\/span>><\/span><\/code><\/span>Code language:<\/span> HTML, XML<\/span> (<\/span>xml<\/span>)<\/span><\/small><\/pre>\n\n\n
Best practices<\/h2>\n\n\n\n
  • Use XML comments<\/strong> for maintainers and echo<\/strong> for runtime visibility.<\/li>
  • Choose log levels intentionally: warning<\/code>\/error<\/code> for important messages, debug<\/code> for deep diagnostics.<\/li>
  • Avoid excessive echo noise in frequently executed targets.<\/li>
  • When generating files with echo file=<\/code>, be explicit about append<\/code> to prevent accidental overwrites.<\/li>
  • Run builds in multiple log modes (-q<\/code>, default, -v<\/code>, -d<\/code>) to confirm message visibility is what you expect.<\/li><\/ul>\n","protected":false},"excerpt":{"rendered":"
    Learn the correct way to add comments in Apache Ant and when to use the echo task instead. This guide covers echo attributes, log-level behavior, and practical build.xml examples.<\/p>\n","protected":false},"author":1,"featured_media":4418,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_joinchat":[],"footnotes":""},"categories":[12],"tags":[209,4238,4239,4242,4243,4235,4237,4236,1122,3113,4241,919,4240,104],"class_list":["post-278","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-apache-ant","tag-ant","tag-ant-comment-block","tag-ant-commenting","tag-ant-comments","tag-ant-multiline-comments","tag-comment","tag-comments-in-ant-build","tag-comments-in-apache-ant","tag-guide","tag-how-to","tag-how-to-put-comment-in-ant","tag-instructions","tag-method","tag-tutorials"],"_links":{"self":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts\/278","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/comments?post=278"}],"version-history":[{"count":4,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts\/278\/revisions"}],"predecessor-version":[{"id":79107,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts\/278\/revisions\/79107"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/media\/4418"}],"wp:attachment":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/media?parent=278"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/categories?post=278"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/tags?post=278"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}