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#+TITLE: task for java #+AUTHOR: Wensheng Xie #+EMAIL: wxie@member.fsf.org #+LANGUAGE: en #+OPTIONS: H:2 num:nil toc:nil \n:nil @:t ::t |:t ^:{} _:{} *:t TeX:t LaTeX:t #+STYLE: #+LATEX_CLASS: myclass #+LATEX_CLASS_OPTIONS: [a4paper] #+ATTR_LATEX: width=0.38\textwidth wrap placement={r}{0.4\textwidth} #+ATTR_LATEX: :float multicolumn #+REVEAL_TRANS: None #+REVEAL_THEME: Black #+TAGS: @work(w) @home(h) @road(r) laptop(l) pc(p) { @read : @read_book @read_ebook } #+ATTR_ORG: :width 30 #+ATTR_HTML: width=”100px” #+EXPORT_SELECT_TAGS: export #+EXPORT_EXCLUDE_TAGS: noexport #+STARTUP: fold

• tasks for java development in emacs ** [2020] * [2020-10] ** [2020-10-28 三] ***** DONE read about bash error handling [1/1] CLOSED: [2020-10-28 三 16:53] - CLOSING NOTE [2020-10-28 三 16:53]
  learned
• [[https://wizardzines.com/comics/bash-errors/][Bash error handling]] ** by default, bash will continue after errors ** ~set -e~ stops the script on errors #+BEGIN_SRC shell set -e unzip fle.zip # script stops here because of typo #+END_SRC ** by default, unset variables don’t error #+BEGIN_SRC shell rm -r “$HOME/$SOMEPTH” # when $SOMEPTH doesn’t exist, use an empty string #+END_SRC ** ~set -u~ stops the script on unset variables #+BEGIN_SRC shell set -u echo $UNSET #script stops here because $UNSET not known #+END_SRC ** by default, a command failing doesn’t fail the whole pipeline #+BEGIN_SRC shell curl 404.html | grep ‘panda’ #curl failed, but grep ok, so all ok #+END_SRC ** ~set -o pipefail~ prevents this #+BEGIN_SRC shell set -euo pipefail #put this at the beginning of your scripts #+END_SRC ***** summary #+BEGIN_SRC shell #!/usr/bin/env > #!/bin/bash

set -o pipefail # trace ERR through pipes set -o errtrace # trace ERR through ‘time command’ and other functions set -o nounset ## set -u : exit the script if you try to use an uninitialised variable set -o errexit ## set -e : exit the script if any statement returns a non-true return value

exec 2>”$stderr_log” # standard error output #+END_SRC