mirror of
https://github.com/flokoe/bash-hackers-wiki.git
synced 2024-11-01 23:03:05 +01:00
51 lines
48 KiB
HTML
51 lines
48 KiB
HTML
|
<!doctype html><html lang=en class=no-js> <head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><link href=https://flokoe.github.io/bash-hackers-wiki/commands/builtin/caller/ rel=canonical><link href=../../classictest/ rel=prev><link href=../cd/ rel=next><link rel=icon href=../../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.5.40"><title>The caller builtin command - The Bash Hackers Wiki</title><link rel=stylesheet href=../../../assets/stylesheets/main.8c3ca2c6.min.css><link rel=stylesheet href=../../../assets/stylesheets/palette.06af60db.min.css><link rel=preconnect href=https://fonts.gstatic.com crossorigin><link rel=stylesheet href="https://fonts.googleapis.com/css?family=Roboto:300,300i,400,400i,700,700i%7CRoboto+Mono:400,400i,700,700i&display=fallback"><style>:root{--md-text-font:"Roboto";--md-code-font:"Roboto Mono"}</style><script>__md_scope=new URL("../../..",location),__md_hash=e=>[...e].reduce(((e,_)=>(e<<5)-e+_.charCodeAt(0)),0),__md_get=(e,_=localStorage,t=__md_scope)=>JSON.parse(_.getItem(t.pathname+"."+e)),__md_set=(e,_,t=localStorage,a=__md_scope)=>{try{t.setItem(a.pathname+"."+e,JSON.stringify(_))}catch(e){}}</script></head> <body dir=ltr data-md-color-scheme=default data-md-color-primary=indigo data-md-color-accent=indigo> <input class=md-toggle data-md-toggle=drawer type=checkbox id=__drawer autocomplete=off> <input class=md-toggle data-md-toggle=search type=checkbox id=__search autocomplete=off> <label class=md-overlay for=__drawer></label> <div data-md-component=skip> <a href=#the-caller-builtin-command class=md-skip> Skip to content </a> </div> <div data-md-component=announce> </div> <header class=md-header data-md-component=header> <nav class="md-header__inner md-grid" aria-label=Header> <a href=../../.. title="The Bash Hackers Wiki" class="md-header__button md-logo" aria-label="The Bash Hackers Wiki" data-md-component=logo> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M12 8a3 3 0 0 0 3-3 3 3 0 0 0-3-3 3 3 0 0 0-3 3 3 3 0 0 0 3 3m0 3.54C9.64 9.35 6.5 8 3 8v11c3.5 0 6.64 1.35 9 3.54 2.36-2.19 5.5-3.54 9-3.54V8c-3.5 0-6.64 1.35-9 3.54"/></svg> </a> <label class="md-header__button md-icon" for=__drawer> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M3 6h18v2H3zm0 5h18v2H3zm0 5h18v2H3z"/></svg> </label> <div class=md-header__title data-md-component=header-title> <div class=md-header__ellipsis> <div class=md-header__topic> <span class=md-ellipsis> The Bash Hackers Wiki </span> </div> <div class=md-header__topic data-md-component=header-topic> <span class=md-ellipsis> The caller builtin command </span> </div> </div> </div> <form class=md-header__option data-md-component=palette> <input class=md-option data-md-color-media data-md-color-scheme=default data-md-color-primary=indigo data-md-color-accent=indigo aria-label="Switch to dark mode" type=radio name=__palette id=__palette_0> <label class="md-header__button md-icon" title="Switch to dark mode" for=__palette_1 hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M12 8a4 4 0 0 0-4 4 4 4 0 0 0 4 4 4 4 0 0 0 4-4 4 4 0 0 0-4-4m0 10a6 6 0 0 1-6-6 6 6 0 0 1 6-6 6 6 0 0 1 6 6 6 6 0 0 1-6 6m8-9.31V4h-4.69L12 .69 8.69 4H4v4.69L.69 12 4 15.31V20h4.69L12 23.31 15.31 20H20v-4.69L23.31 12z"/></svg> </label> <input class=md-option data-md-color-media data-md-color-scheme=slate data-md-color-primary=indigo data-md-color-accent=indigo aria-label="Switch to light mode" type=radio name=__palette id=__palette_1> <label class="md-header__button md-icon" title="Switch to light mode" for=__palette_0 hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M12 18c-.89 0-1.74-.2-2.5-.55C11.56 16.5 13 14.42 13 12s-1.44-4.5-3.5-5.45C10.26 6.2 11.11 6 12 6a6 6 0 0 1 6 6 6 6 0 0 1-6 6m8-9.31V4h-4.69L12 .69 8.69 4H4v4.69L.69 12 4 15.31V20h4.69L12 23.31 15.31 20H20v-4.69L23.31 12z"/></svg> </label> </form> <script>var palette=__md_get("__palette");if(palette&&palette.color){if("(prefers-color-scheme)"===palette.color.me
|
||
|
|
</code></pre></div> <h2 id=description>Description<a class=headerlink href=#description title="Permanent link">¶</a></h2> <p>The <code>caller</code> builtin command is used to print execution frames of subroutine calls. Without giving a framenumber, the topmost execution frame information is printed ("who called me") wile linenumber and filename.</p> <p>When an execution frame number is given (0 - topmost), the linenumber, the subroutine (function) and the filename is printed. When an invalid execution frame number is given, it exists <code>FALSE</code>. This way it can be used in a loop (see the examples section below).</p> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">¶</a></h2> <h3 id=simple-stack-trace>Simple stack trace<a class=headerlink href=#simple-stack-trace title="Permanent link">¶</a></h3> <p>The code below defines a function <code>die</code> that is used to exit the program. It prints a list of execution frames, starting with the topmost frame (0). The topmost frame is the "caller of the die function", in this case function "f1".</p> <p>This way, you can print a "stack trace" for debugging or logging purposes.</p> <p>The code is made very simple, just to show the basic purposes.</p> <div class=highlight><pre><span></span><code><a id=__codelineno-0-1 name=__codelineno-0-1 href=#__codelineno-0-1></a><span class=ch>#!/bin/bash</span>
|
||
|
|
<a id=__codelineno-0-2 name=__codelineno-0-2 href=#__codelineno-0-2></a>
|
||
|
|
<a id=__codelineno-0-3 name=__codelineno-0-3 href=#__codelineno-0-3></a>die<span class=o>()</span><span class=w> </span><span class=o>{</span>
|
||
|
|
<a id=__codelineno-0-4 name=__codelineno-0-4 href=#__codelineno-0-4></a><span class=w> </span><span class=nb>local</span><span class=w> </span><span class=nv>frame</span><span class=o>=</span><span class=m>0</span>
|
||
|
|
<a id=__codelineno-0-5 name=__codelineno-0-5 href=#__codelineno-0-5></a><span class=w> </span><span class=k>while</span><span class=w> </span><span class=nb>caller</span><span class=w> </span><span class=nv>$frame</span><span class=p>;</span><span class=w> </span><span class=k>do</span>
|
||
|
|
<a id=__codelineno-0-6 name=__codelineno-0-6 href=#__codelineno-0-6></a><span class=w> </span><span class=o>((</span>++frame<span class=o>))</span><span class=p>;</span>
|
||
|
|
<a id=__codelineno-0-7 name=__codelineno-0-7 href=#__codelineno-0-7></a><span class=w> </span><span class=k>done</span>
|
||
|
|
<a id=__codelineno-0-8 name=__codelineno-0-8 href=#__codelineno-0-8></a><span class=w> </span><span class=nb>echo</span><span class=w> </span><span class=s2>"</span><span class=nv>$*</span><span class=s2>"</span>
|
||
|
|
<a id=__codelineno-0-9 name=__codelineno-0-9 href=#__codelineno-0-9></a><span class=w> </span><span class=nb>exit</span><span class=w> </span><span class=m>1</span>
|
||
|
|
<a id=__codelineno-0-10 name=__codelineno-0-10 href=#__codelineno-0-10></a><span class=o>}</span>
|
||
|
|
<a id=__codelineno-0-11 name=__codelineno-0-11 href=#__codelineno-0-11></a>
|
||
|
|
<a id=__codelineno-0-12 name=__codelineno-0-12 href=#__codelineno-0-12></a>f1<span class=o>()</span><span class=w> </span><span class=o>{</span><span class=w> </span>die<span class=w> </span><span class=s2>"*** an error occured ***"</span><span class=p>;</span><span class=w> </span><span class=o>}</span>
|
||
|
|
<a id=__codelineno-0-13 name=__codelineno-0-13 href=#__codelineno-0-13></a>f2<span class=o>()</span><span class=w> </span><span class=o>{</span><span class=w> </span>f1<span class=p>;</span><span class=w> </span><span class=o>}</span>
|
||
|
|
<a id=__codelineno-0-14 name=__codelineno-0-14 href=#__codelineno-0-14></a>f3<span class=o>()</span><span class=w> </span><span class=o>{</span><span class=w> </span>f2<span class=p>;</span><span class=w> </span><span class=o>}</span>
|
||
|
|
<a id=__codelineno-0-15 name=__codelineno-0-15 href=#__codelineno-0-15></a>
|
||
|
|
<a id=__codelineno-0-16 name=__codelineno-0-16 href=#__codelineno-0-16></a>f3
|
||
|
|
</code></pre></div> <p><strong>Output</strong></p> <div class=highlight><pre><span></span><code>12 f1 ./callertest.sh
|
||
|
|
13 f2 ./callertest.sh
|
||
|
|
14 f3 ./callertest.sh
|
||
|
|
16 main ./callertest.sh
|
||
|
|
*** an error occured ***
|
||
|
|
</code></pre></div> <h2 id=notes>Notes<a class=headerlink href=#notes title="Permanent link">¶</a></h2> <ul> <li><code>caller</code> produces no output unless used within a script that's run from a real file. It isn't particularly useful for interactive use, but can be used to create a decent <code>die</code> function to track down errors in moderately complex scripts. <code>{ bash /dev/stdin; } <<<$'f(){ g; }\ng(){ h; }\nh(){ while caller $((n++)); do :; done; }\nf'</code></li> <li>For more sophisticated debugging, Bash extended debugging features are available and a number of special parameters that give more detail than caller (e.g. BASH_ARG{C,V}). Tools such as <a href=http://bashdb.sourceforge.net/ >Bashdb</a> can assist in using some of Bash's more advanced debug features.</li> <li>The Bash manpage and help text specifies that the argument to <code>caller</code> is an "expr" (whatever that means). Only an integer is actually allowed, with no special interpretation of an "expression" as far as we can tell.</li> </ul> <h2 id=portability-considerations>Portability considerations<a class=headerlink href=#portability-considerations title="Permanent link">¶</a></h2> <ul> <li><code>caller</code> is not specified by POSIX(R)</li> <li>the <code>caller</code> builtin command appeared in Bash version 3.0</li> </ul> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">¶</a></h2> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date">October 12, 2024</span> </span> <span class=md-source-file__fact> <span class=md-icon title=Created> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M14.47 15.08 11 13V7h1.5v5.25l3.08 1.83c-.41.28-.79.62-1.11 1m-1.39 4.84c-.36.05-.71.08-1.08.08-4.42 0-8-3.58-8-8s3.58-8 8-8 8 3.58 8 8c0 .37-.03.72-.08 1.08.69.1 1.33.32 1.92.64.1-.56.16-1.13.16-1.72 0-5.5-4.5-10-10-10S2 6.5 2 12s4.47 10 10 10c.59 0 1.16-.06 1.72-.16-.32-.59-.54-1.23-.64-1.92M18 15v3h-3v2h3v3h2v-3h3v-2h-3v-3z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date">October 12, 2024</span> </span> </aside> <h2 id=__comments>Comments</h2> <script src=https://giscus.app/client.js data-repo=flokoe/bash-hackers-wiki data-repo-id=R_kgDOJ3Nr6Q data-category="Giscus Page Comments" data-category-id=DIC_kwDOJ3Nr6c4CXq9t data-mapping=pathname data-strict=1 data-reactions-enabled=1 data-emit-metadata=0 data-input-position=top data-theme=preferred_color_scheme data-lang=en data-loading=lazy crossorigin=anonymous async>
|
||
|
|
</script> <script>
|
||
|
|
var giscus = document.querySelector("script[src*=giscus]")
|
||
|
|
|
||
|
|
/* Set palette on initial load */
|
||
|
|
var palette = __md_get("__palette")
|
||
|
|
if (palette && typeof palette.color === "object") {
|
||
|
|
var theme = palette.color.scheme === "slate" ? "dark" : "light"
|
||
|
|
giscus.setAttribute("data-theme", theme)
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Register event handlers after documented loaded */
|
||
|
|
document.addEventListener("DOMContentLoaded", function() {
|
||
|
|
var ref = document.querySelector("[data-md-component=palette]")
|
||
|
|
ref.addEventListener("change", function() {
|
||
|
|
var palette = __md_get("__palette")
|
||
|
|
if (palette && typeof palette.color === "object") {
|
||
|
|
var theme = palette.color.scheme === "slate" ? "dark" : "light"
|
||
|
|
|
||
|
|
/* Instruct Giscus to change theme */
|
||
|
|
var frame = document.querySelector(".giscus-frame")
|
||
|
|
frame.contentWindow.postMessage(
|
||
|
|
{ giscus: { setConfig: { theme } } },
|
||
|
|
"https://giscus.app"
|
||
|
|
)
|
||
|
|
}
|
||
|
|
})
|
||
|
|
})
|
||
|
|
</script> </article> </div> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> Made with <a href=https://squidfunk.github.io/mkdocs-material/ target=_blank rel=noopener> Material for MkDocs </a> </div> </div> </div> </footer> </div> <div class=md-dialog data-md-component=dialog> <div class="md-dialog__inner md-typeset"></div> </div> <script id=__config type=application/json>{"base": "../../..", "features": ["navigation.instant", "navigation.tracking", "navigation.tabs", "navigation.sections", "navigation.top", "content.action.view", "content.action.edit", "search.suggest", "search.highlight", "content.code.copy"], "search": "../../../assets/javascripts/workers/search.6ce7567c.min.js", "translations": {"clipboard.copied": "Copied to clipboard", "clipboard.copy": "Copy to clipboard", "search.result.more.one": "1 more on this page", "search.result.more.other": "# more on this page", "search.result.none": "No matching documents", "search.result.one": "1 matching document", "search.result.other": "# matching documents", "search.result.placeholder": "Type to start searching", "search.result.term.missing": "Missing", "select.version": "Select version"}}</script> <script src=../../../assets/javascripts/bundle.525ec568.min.js></script> </body> </html>
|