From 020c1e77489b772f854bb3288b9c8d2818a6bf9d Mon Sep 17 00:00:00 2001 From: EuAndreh Date: Fri, 18 Apr 2025 02:17:12 -0300 Subject: git mv src/content/* src/content/en/ --- .../en/tils/2020/08/12/filename-timestamp.adoc | 31 ++++ src/content/en/tils/2020/08/13/code-jekyll.adoc | 159 ++++++++++++++++++++ src/content/en/tils/2020/08/14/browse-git.adoc | 76 ++++++++++ src/content/en/tils/2020/08/16/git-search.adoc | 49 ++++++ src/content/en/tils/2020/08/28/grep-online.adoc | 133 +++++++++++++++++ .../en/tils/2020/09/04/cli-email-fun-profit.adoc | 76 ++++++++++ src/content/en/tils/2020/09/05/oldschool-pr.adoc | 110 ++++++++++++++ .../en/tils/2020/10/11/search-git-history.adoc | 29 ++++ .../en/tils/2020/11/08/find-broken-symlink.adoc | 25 ++++ .../en/tils/2020/11/12/diy-nix-bash-ci.adoc | 63 ++++++++ .../en/tils/2020/11/12/git-bisect-automation.adoc | 25 ++++ .../en/tils/2020/11/12/useful-bashvars.adoc | 61 ++++++++ src/content/en/tils/2020/11/14/gpodder-media.adoc | 21 +++ src/content/en/tils/2020/11/30/git-notes-ci.adoc | 112 ++++++++++++++ .../en/tils/2020/12/15/shellcheck-repo.adoc | 165 +++++++++++++++++++++ src/content/en/tils/2020/12/29/svg.adoc | 125 ++++++++++++++++ 16 files changed, 1260 insertions(+) create mode 100644 src/content/en/tils/2020/08/12/filename-timestamp.adoc create mode 100644 src/content/en/tils/2020/08/13/code-jekyll.adoc create mode 100644 src/content/en/tils/2020/08/14/browse-git.adoc create mode 100644 src/content/en/tils/2020/08/16/git-search.adoc create mode 100644 src/content/en/tils/2020/08/28/grep-online.adoc create mode 100644 src/content/en/tils/2020/09/04/cli-email-fun-profit.adoc create mode 100644 src/content/en/tils/2020/09/05/oldschool-pr.adoc create mode 100644 src/content/en/tils/2020/10/11/search-git-history.adoc create mode 100644 src/content/en/tils/2020/11/08/find-broken-symlink.adoc create mode 100644 src/content/en/tils/2020/11/12/diy-nix-bash-ci.adoc create mode 100644 src/content/en/tils/2020/11/12/git-bisect-automation.adoc create mode 100644 src/content/en/tils/2020/11/12/useful-bashvars.adoc create mode 100644 src/content/en/tils/2020/11/14/gpodder-media.adoc create mode 100644 src/content/en/tils/2020/11/30/git-notes-ci.adoc create mode 100644 src/content/en/tils/2020/12/15/shellcheck-repo.adoc create mode 100644 src/content/en/tils/2020/12/29/svg.adoc (limited to 'src/content/en/tils/2020') diff --git a/src/content/en/tils/2020/08/12/filename-timestamp.adoc b/src/content/en/tils/2020/08/12/filename-timestamp.adoc new file mode 100644 index 0000000..aa8d63b --- /dev/null +++ b/src/content/en/tils/2020/08/12/filename-timestamp.adoc @@ -0,0 +1,31 @@ += Simple filename timestamp +:categories: shell + +When writing Jekyll posts or creating log files with dates on them, I usually +struggle with finding a direct way of accomplishing that. There's a simple +solution: `date -I`. + +[source,sh] +---- +./my-program.sh > my-program.$(date -I).log +cp post-template.md _posts/$(date -I)-post-slug.md +---- + +Using this built-in GNU/Linux tool allows you to `touch $(date -I).md` to +readily create a `2020-08-12.md` file. + +I always had to read `man date` or search the web over and over, and after doing +this repeatedly it became clear that both `date -I` and `date -Is` (`s` here +stands for seconds) are the thing that I'm looking for 95% of the time: + +[source,sh] +---- +# inside my-program.sh +echo "Program started at $(date -Is)" +# output is: +# Program started at 2020-08-12T09:04:58-03:00 +---- + +Both date formats are hierarchical, having the bigger time intervals to the +left. This means that you can easily sort them (and even tab-complete them) +with no extra effort or tool required. diff --git a/src/content/en/tils/2020/08/13/code-jekyll.adoc b/src/content/en/tils/2020/08/13/code-jekyll.adoc new file mode 100644 index 0000000..6bd90b0 --- /dev/null +++ b/src/content/en/tils/2020/08/13/code-jekyll.adoc @@ -0,0 +1,159 @@ += Anchor headers and code lines in Jekyll + +:empty: +:jekyll: https://jekyllrb.com/ +:kramdown: https://kramdown.gettalong.org/ +:rouge: https://rouge.jneen.net/ +:jekyll-hook: https://jekyllrb.com/docs/plugins/hooks/ + +The default Jekyll toolbox ({jekyll}[Jekyll], {kramdown}[kramdown] and +{rouge}[rouge]) doesn't provide with a configuration option to add anchors to +headers and code blocks. + +The best way I found of doing this is by creating a simple Jekyll plugin, more +specifically, a {jekyll-hook}[Jekyll hook]. These allow you to jump in to the +Jekyll build and add a processing stage before of after Jekyll performs +something. + +All you have to do is add the code to `_plugins/my-jekyll-plugin-code.rb`, and +Jekyll knows to pick it up and call your code on the appropriate time. + +== Anchor on headers + +:jemoji: https://github.com/jekyll/jemoji +:jekyll-mentions: https://github.com/jekyll/jekyll-mentions +:html-regex: https://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags/1732454#1732454 + +Since I wanted to add anchors to headers in all documents, this Jekyll hook +works on `:documents` after they have been transformed into HTML, the +`:post_render` phase: + +[source,ruby] +---- +Jekyll::Hooks.register :documents, :post_render do |doc| + if doc.output_ext == ".html" + doc.output = + doc.output.gsub( + /(.*?)<\/h[1-6]>/, + '\5' + ) + end +end +---- + +I've derived my implementations from two +"official"{empty}footnote:official[ + I don't know how official they are, I just assumed it because they live in the + same organization inside GitHub that Jekyll does. +] hooks, {jemoji}[jemoji] and {jekyll-mentions}[jekyll-mentions]. + +All I did was to wrap the header tag inside an ``, and set the `href` of that +`` to the existing id of the header. Before the hook the HTML looks like: + +[source,html] +---- +...some unmodified text... +

+ My header +

+...more unmodified text... +---- + +And after the hook should turn that into: + +[source,html] +---- +...some unmodified text... + +

+ My header +

+ +...more unmodified text... +---- + +The used regexp tries to match only h1-h6 tags, and keep the rest of the HTML +attributes untouched, since this isn't a general HTML parser, but the generated +HTML is somewhat under your control. Use at your own risk because +{html-regex}[you shouldn't parse HTML with regexps]. Also I used this strategy +in my environment, where no other plugins are installed. I haven't considered +how this approach may conflict with other Jekyll plugins. + +In the new anchor tag you can add your custom CSS class to style it as you wish. + +== Anchor on code blocks + +Adding anchors to code blocks needs a little bit of extra work, because line +numbers themselves don't have preexisting ids, so we need to generate them +without duplications between multiple code blocks in the same page. + +Similarly, this Jekyll hook also works on `:documents` in the `:post_render` +phase: + +[source,ruby] +---- +PREFIX = '
'
+POSTFIX = '
' +Jekyll::Hooks.register :documents, :post_render do |doc| + if doc.output_ext == ".html" + code_block_counter = 1 + doc.output = doc.output.gsub(/
[\n0-9]+<\/pre>/) do |match|
+      line_numbers = match
+                      .gsub(/
([\n0-9]+)<\/pre>/, '\1')
+                      .split("\n")
+
+      anchored_line_numbers_array = line_numbers.map do |n|
+        id = "B#{code_block_counter}-L#{n}"
+        "#{n}"
+      end
+      code_block_counter += 1
+
+      PREFIX + anchored_line_numbers_array.join("\n") + POSTFIX
+    end
+  end
+end
+----
+
+This solution assumes the default Jekyll toolbox with code line numbers turned
+on in `_config.yml`:
+
+[source,yaml]
+----
+kramdown:
+  syntax_highlighter_opts:
+    span:
+      line_numbers: false
+    block:
+      line_numbers: true
+----
+
+The anchors go from B1-L1 to BN-LN, using the `code_block_counter` to track
+which code block we're in and don't duplicate anchor ids.  Before the hook the
+HTML looks like:
+
+[source,html]
+----
+...some unmodified text...
+
1
+2
+3
+4
+5
+

+...more unmodified text...
+----
+
+And after the hook should turn that into:
+
+[source,html]
+----
+...some unmodified text...
+
1
+2
+3
+4
+5

+...more unmodified text...
+----
+
+Happy writing :)
diff --git a/src/content/en/tils/2020/08/14/browse-git.adoc b/src/content/en/tils/2020/08/14/browse-git.adoc
new file mode 100644
index 0000000..6b3ff6d
--- /dev/null
+++ b/src/content/en/tils/2020/08/14/browse-git.adoc
@@ -0,0 +1,76 @@
+= Browse a git repository at a specific commit
+:categories: git
+
+I commonly use tools like `git log` together with `git show` when inspecting
+past changes in a repository:
+
+[source,sh]
+----
+git log
+# search for a the commit I'm looking for
+git show 
+# see the diff for the commit
+----
+
+But I also wanted to not only be able to look at the diff of a specific commit,
+but to browse the whole repository at that specific commit.
+
+I used to accomplish it the "brute force" way: clone the whole repository in
+another folder and checkout the commit there:
+
+[source,sh]
+----
+git clone  /tmp/tmp-repo-clone
+cd /tmp-repo-clone
+git checkout 
+----
+
+But git itself allows we to specific the directory of the checkout by using the
+`--work-tree` global git flag.  This is what `man git` says about it:
+
+[source,text]
+----
+--work-tree=
+    Set the path to the working tree. It can be an absolute path or a path relative to the current working
+    directory. This can also be controlled by setting the GIT_WORK_TREE environment variable and the
+    core.worktree configuration variable (see core.worktree in git-config(1) for a more detailed
+    discussion).
+----
+
+So it allows us to set the desired path of the working tree.  So if we want to
+copy the contents of the current working tree into `copy/`:
+
+[source,sh]
+----
+mkdir copy
+git --work-tree=copy/ checkout .
+----
+
+After that `copy/` will contain a replica of the code in HEAD.  But to checkout
+a specific, we need some extra parameters:
+
+[source,sh]
+----
+git --work-tree= checkout  -- .
+----
+
+There's an extra `-- .` at the end, which initially looks like we're sending
+Morse signals to git, but we're actually saying to `git-checkout` which sub
+directory of `` we want to look at.  Which means we can do something
+like:
+
+[source,sh]
+----
+git --work-tree= checkout  -- src/
+----
+
+And with that `` will only contain what was inside `src/` at ``.
+
+After any of those checkouts, you have to `git reset .` to reset your current
+staging area back to what it was before the checkout.
+
+== References
+
+:so-link: https://stackoverflow.com/a/16493707
+
+. {so-link}[GIT: Checkout to a specific folder] (StackOverflow)
diff --git a/src/content/en/tils/2020/08/16/git-search.adoc b/src/content/en/tils/2020/08/16/git-search.adoc
new file mode 100644
index 0000000..4113f3f
--- /dev/null
+++ b/src/content/en/tils/2020/08/16/git-search.adoc
@@ -0,0 +1,49 @@
+= Search in git
+:categories: git
+
+Here's a useful trio to know about to help you search things in git:
+
+. `git show `
+. `git log --grep=''`
+. `git grep '' [commit]`
+
+== 1. `git show `
+
+Show a specific commit and it's diff:
+
+[source,sh]
+----
+git show
+# shows the latest commit
+git show 
+# shows an specific 
+git show v1.2
+# shows commit tagged with v1.2
+----
+
+== 2. `git log --grep=''`
+
+Search through the commit messages:
+
+[source,sh]
+----
+git log --grep='refactor'
+----
+
+== 3. `git grep '' [commit]`
+
+:browse-article: link:../14/browse-git.html
+
+Search content in git history:
+
+[source,sh]
+----
+git grep 'TODO'
+# search the repository for the "TODO" string
+git grep 'TODO' $(git rev-list --all)
+# search the whole history for "TODO" string
+----
+
+And if you find an occurrence of the regexp in a specific commit and you want to
+browse the repository in that point in time, you can {browse-article}[use git
+checkout for that].
diff --git a/src/content/en/tils/2020/08/28/grep-online.adoc b/src/content/en/tils/2020/08/28/grep-online.adoc
new file mode 100644
index 0000000..77363ab
--- /dev/null
+++ b/src/content/en/tils/2020/08/28/grep-online.adoc
@@ -0,0 +1,133 @@
+= Grep online repositories
+:categories: git
+
+:cgit: https://git.zx2c4.com/cgit/
+
+I often find interesting source code repositories online that I want to grep for
+some pattern but I can't, because either:
+
+* the repository is on {cgit}[cgit] or a similar code repository that doesn't
+  allow search in files, or;
+* the search function is really bad, and doesn't allow me to use regular
+  expressions for searching patterns in the code.
+
+Here's a simple script that allows you to overcome that problem easily:
+
+[source,sh]
+----
+#!/usr/bin/env bash
+set -eu
+
+end="\033[0m"
+red="\033[0;31m"
+red() { echo -e "${red}${1}${end}"; }
+
+usage() {
+  red "Missing argument $1.\n"
+  cat < 
+
+      Arguments:
+        REGEX_PATTERN     Regular expression that "git grep" can search
+        REPOSITORY_URL    URL address that "git clone" can download the repository from
+
+Examples:
+    Searching "make get-git" in cgit repository:
+        git search 'make get-git' https://git.zx2c4.com/cgit/
+        git search 'make get-git' https://git.zx2c4.com/cgit/ -- \$(git rev-list --all)
+EOF
+  exit 2
+}
+
+
+REGEX_PATTERN="${1:-}"
+REPOSITORY_URL="${2:-}"
+[[ -z "${REGEX_PATTERN}" ]] && usage 'REGEX_PATTERN'
+[[ -z "${REPOSITORY_URL}" ]] && usage 'REPOSITORY_URL'
+
+mkdir -p /tmp/git-search
+DIRNAME="$(echo "${REPOSITORY_URL%/}" | rev | cut -d/ -f1 | rev)"
+if [[ ! -d "/tmp/git-search/${DIRNAME}" ]]; then
+  git clone "${REPOSITORY_URL}" "/tmp/git-search/${DIRNAME}"
+fi
+pushd "/tmp/git-search/${DIRNAME}"
+
+shift 3 || shift 2 # when "--" is missing
+git grep "${REGEX_PATTERN}" "${@}"
+----
+
+It is a wrapper around `git grep` that downloads the repository when missing.
+Save in a file called `git-search`, make the file executable and add it to your
+path.
+
+Overview:
+
+* _lines 1~2_:
++
+Bash shebang and the `set -eu` options to exit on error or undefined
+variables.
+
+* _lines 4~30_:
++
+Usage text to be printed when providing less arguments than expected.
+
+* _line 33_:
++
+Extract the repository name from the URL, removing trailing slashes.
+
+* _lines 34~37_:
++
+Download the repository when missing and go to the folder.
+
+* _line 39_:
++
+Make the variable `$@` contain the rest of the unused arguments.
+
+* _line 40_:
++
+Perform `git grep`, forwarding the remaining arguments from `$@`.
+
+Example output:
+
+[source,sh]
+----
+$ git search 'make get-git' https://git.zx2c4.com/cgit/
+Clonage dans '/tmp/git-search/cgit'...
+remote: Enumerating objects: 542, done.
+remote: Counting objects: 100% (542/542), done.
+remote: Compressing objects: 100% (101/101), done.
+warning: object 51dd1eff1edc663674df9ab85d2786a40f7ae3a5: gitmodulesParse: could not parse gitmodules blob
+remote: Total 7063 (delta 496), reused 446 (delta 441), pack-reused 6521
+Réception d'objets: 100% (7063/7063), 8.69 Mio | 5.39 Mio/s, fait.
+Résolution des deltas: 100% (5047/5047), fait.
+/tmp/git-search/cgit ~/dev/libre/songbooks/docs
+README:    $ make get-git
+
+$ git search 'make get-git' https://git.zx2c4.com/cgit/
+/tmp/git-search/cgit ~/dev/libre/songbooks/docs
+README:    $ make get-git
+----
+
+Subsequent greps on the same repository are faster because no download is
+needed.
+
+When no argument is provided, it prints the usage text:
+
+[source,sh]
+----
+$ git search
+Missing argument REGEX_PATTERN.
+
+Usage:
+    /home/andreh/dev/libre/dotfiles/scripts/ad-hoc/git-search  
+
+      Arguments:
+        REGEX_PATTERN     Regular expression that "git grep" can search
+        REPOSITORY_URL    URL address that "git clone" can download the repository from
+
+Examples:
+    Searching "make get-git" in cgit repository:
+        git search 'make get-git' https://git.zx2c4.com/cgit/
+        git search 'make get-git' https://git.zx2c4.com/cgit/ -- $(git rev-list --all)
+----
diff --git a/src/content/en/tils/2020/09/04/cli-email-fun-profit.adoc b/src/content/en/tils/2020/09/04/cli-email-fun-profit.adoc
new file mode 100644
index 0000000..1da1154
--- /dev/null
+++ b/src/content/en/tils/2020/09/04/cli-email-fun-profit.adoc
@@ -0,0 +1,76 @@
+= Send emails using the command line for fun and profit!
+
+:ssmtp: https://wiki.archlinux.org/index.php/SSMTP
+:mailutils: https://mailutils.org/
+
+Here are a few reasons why:
+
+. send yourself and other people notification of cronjobs, scripts runs, CI
+  jobs, _etc._
+. leverage the POSIX pipe `|`, and pipe emails away!
+. because you can.
+
+Reason 3 is the fun part, reasons 1 and 2 are the profit part.
+
+First {ssmpt}[install and configure SSMTP] for using, say, Gmail as the email
+server:
+
+[source,sh]
+----
+# file /etc/ssmtp/ssmtp.conf
+FromLineOverride=YES
+MailHub=smtp.gmail.com:587
+UseSTARTTLS=YES
+UseTLS=YES
+rewriteDomain=gmail.com
+root=username@gmail.com
+AuthUser=username
+AuthPass=password
+----
+
+Now install {mailutils}[GNU Mailutils] (`sudo apt-get install mailutils` or the
+equivalent on your OS), and send yourself your first email:
+
+[source,sh]
+----
+echo body | mail -aFrom:email@example.com email@example.com -s subject
+----
+
+And that's about it, you've got mail.  Here are some more places where it might
+be applicable:
+
+[source,sh]
+----
+# report a backup cronjob, attaching logs
+set -e
+
+finish() {
+  status=$?
+  if [[ $status = 0 ]]; then
+    STATUS="SUCCESS (status $status)"
+  else
+    STATUS="FAILURE (status $status)"
+  fi
+
+  mail user@example.com                                 \
+       -s "Backup job report on $(hostname): ${STATUS}" \
+       --content-type 'text/plain; charset=utf-8'       \
+       -A"$LOG_FILE" <<< 'The log report is in the attachment.'
+}
+trap finish EXIT
+
+do-long-backup-cmd-here
+----
+
+[source,sh]
+----
+# share the output of a cmd with someone
+some-program | mail someone@example.com -s "The weird logs that I was talking about"
+----
+
+...and so on.
+
+You may consider adding a `alias mail='mail -aFrom:email@example.com'` so you
+don't keep re-entering the ``From:'' part.
+
+Send yourself some emails to see it working!
diff --git a/src/content/en/tils/2020/09/05/oldschool-pr.adoc b/src/content/en/tils/2020/09/05/oldschool-pr.adoc
new file mode 100644
index 0000000..392ec67
--- /dev/null
+++ b/src/content/en/tils/2020/09/05/oldschool-pr.adoc
@@ -0,0 +1,110 @@
+= Pull requests with Git, the old school way
+:categories: git
+
+:empty:
+:cgit: https://git.zx2c4.com/cgit/
+
+It might be news to you, as it was to me, that "pull requests" that you can
+create on a Git hosting provider’s web
+UI{empty}footnote:pr-webui[
+  And maybe even using the Git hosting provider’s API from the command line!
+] like GitLab/Bitbucket/GitHub actually comes from Git itself:
+`git request-pull`.
+
+At the very core, they accomplish the same thing: both the original and the web
+UI ones are ways for you to request the project maintainers to pull in your
+changes from your fork.  It’s like saying: "hi there, I did some changes on my
+clone of the repository, what do you think about bringing those in?".
+
+The only difference is that you’re working with only Git itself, so you’re not
+tied to any Git hosting provider: you can send pull requests across them
+transparently!  You could even use your own {cgit}[cgit] installation.  No need
+to be locked in by any of them, putting the "D" back in "DVCS": it’s a
+*distributed* version control system.
+
+== `git request-pull` introduction
+
+Here’s the raw output of a `git request-pull`:
+
+[source,sh]
+----
+$ git request-pull HEAD public-origin
+The following changes since commit 302c9f2f035c0360acd4e13142428c100a10d43f:
+
+  db post: Add link to email exchange (2020-09-03 21:23:55 -0300)
+
+are available in the Git repository at:
+
+  https://euandre.org/git/euandre.org/
+
+for you to fetch changes up to 524c646cdac4153e54f2163e280176adbc4873fa:
+
+  db post: better pinpoint sqlite unsuitability (2020-09-03 22:08:56 -0300)
+
+----------------------------------------------------------------
+EuAndreh (1):
+      db post: better pinpoint sqlite unsuitability
+
+ _posts/2020-08-31-the-database-i-wish-i-had.md | 12 ++++++------
+ 1 file changed, 6 insertions(+), 6 deletions(-)
+----
+
+That very first line is saying: "create me a pull request with only a single
+commit, defined by `HEAD`, and use the URL defined by `public-origin`".
+
+Here’s a pitfall: you may try using your `origin` remote at first where I put
+`public-origin`, but that is many times pointing to something like
+`git@example.com`, or `git.example.com:repo.git` (check that with
+`git remote -v | grep origin`).  On both cases those are addresses available for
+interaction via SSH, and it would be better if your pull requests used an
+address ready for public consumption.
+
+A simple solution for that is for you to add the `public-origin` alias as the
+HTTPS alternative to the SSH version:
+
+[source,sh]
+----
+$ git remote add public-origin https://example.com/user/repo
+----
+
+Every Git hosting provider exposes repositories via HTTPS.
+
+Experiment it yourself, and get acquainted with the CLI.
+
+== Delivering decentralized pull requests
+
+:cli-email: link:../04/cli-email-fun-profit.html
+
+Now that you can create the content of a pull request, you can just
+{cli-email}[deliver it] to the interested parties email:
+
+[source,sh]
+----
+# send a PR with your last commit to the author's email
+git request-pull HEAD public-origin | mail author@example.com -s "PR: Add thing to repo"
+
+# send a PR with your last 5 commits to the project's mailing
+# list, including the patch
+git request-pull -p HEAD~5 public-origin | \
+  mail list@example.com -s "PR: Add another thing to repo"
+
+# send every commit that is new in "other-branch"
+git request-pull master public-origin other-branch | \
+  mail list@example.com -s 'PR: All commits from my "other-brach"'
+----
+
+== Conclusion
+
+:distgit: https://drewdevault.com/2018/07/23/Git-is-already-distributed.html
+
+In practice, I’ve never used or seen anyone use pull requests this way:
+everybody is just {distgit}[sending patches via email].
+
+If you stop to think about this model, the problem of "Git hosting providers
+becoming too centralized" is a non-issue, and "Git federation" proposals are a
+less attractive as they may sound initially.
+
+Using Git this way is not scary or so weird as the first impression may suggest.
+It is actually how Git was designed to be used.
+
+Check `git help request-pull` for more info.
diff --git a/src/content/en/tils/2020/10/11/search-git-history.adoc b/src/content/en/tils/2020/10/11/search-git-history.adoc
new file mode 100644
index 0000000..696368c
--- /dev/null
+++ b/src/content/en/tils/2020/10/11/search-git-history.adoc
@@ -0,0 +1,29 @@
+= Search changes to a filename pattern in Git history
+:categories: git
+
+:yet:     link:../../08/14/browse-git.html
+:another: link:../../08/16/git-search.html
+:entry:   link:../../08/28/grep-online.html
+
+This is {yet}[yet] {another}[another] {entry}["search in Git"] TIL entry.  You
+could say that Git has a unintuitive CLI, or that is it very powerful.
+
+I wanted to search for an old file that I new that was in the history of the
+repository, but was deleted some time ago.  So I didn't really remember the
+name, only bits of it.
+
+I immediately went to the list of TILs I had written on searching in Git, but it
+wasn't readily obvious how to do it, so here it goes:
+
+[source,sh]
+----
+git log -- *pattern*
+----
+
+You could add globs before the pattern to match things on any directory, and add
+our `-p` friend to promptly see the diffs:
+
+[source,sh]
+----
+git log -p -- **/*pattern*
+----
diff --git a/src/content/en/tils/2020/11/08/find-broken-symlink.adoc b/src/content/en/tils/2020/11/08/find-broken-symlink.adoc
new file mode 100644
index 0000000..624d24a
--- /dev/null
+++ b/src/content/en/tils/2020/11/08/find-broken-symlink.adoc
@@ -0,0 +1,25 @@
+= Find broken symlinks with "find"
+:categories: shell
+
+:annex:        https://git-annex.branchable.com/
+:annex-wanted: https://git-annex.branchable.com/git-annex-wanted/
+
+The `find` command knows how to show broken symlinks:
+
+[source,sh]
+----
+find . -xtype l
+----
+
+This was useful to me when combined with {annex}[Git Annex].  Its
+{annex-wanted}[`wanted`] option allows you to have a "sparse" checkout of the
+content, and save space by not having to copy every annexed file locally:
+
+[source,sh]
+----
+git annex wanted . 'exclude=Music/* and exclude=Videos/*'
+----
+
+You can `find` any broken symlinks outside those directories by querying with
+Git Annex itself, but `find . -xtype l` works on other places too, where broken
+symlinks might be a problem.
diff --git a/src/content/en/tils/2020/11/12/diy-nix-bash-ci.adoc b/src/content/en/tils/2020/11/12/diy-nix-bash-ci.adoc
new file mode 100644
index 0000000..97ace30
--- /dev/null
+++ b/src/content/en/tils/2020/11/12/diy-nix-bash-ci.adoc
@@ -0,0 +1,63 @@
+= DIY bare bones CI server with Bash and Nix
+:categories: ci
+:sort: 2
+
+:post-receive: https://git-scm.com/book/en/v2/Customizing-Git-Git-Hooks
+:example-project: https://euandreh.xyz/remembering/ci.html
+
+With a server with Nix installed (no need for NixOS), you can leverage its build
+isolation for running CI jobs by adding a {post-receive}[post-receive] Git hook
+to the server.
+
+In most of my project I like to keep a `test` attribute which runs the test with
+`nix-build -A test`.  This way, a post-receive hook could look like:
+
+[source,sh]
+----
+#!/usr/bin/env bash
+set -Eeuo pipefail
+set -x
+
+LOGS_DIR="/data/static/ci-logs/libedn"
+mkdir -p "$LOGS_DIR"
+LOGFILE="${LOGS_DIR}/$(date -Is)-$(git rev-parse master).log"
+exec &> >(tee -a "${LOGFILE}")
+
+unset GIT_DIR
+CLONE="$(mktemp -d)"
+git clone . "$CLONE"
+pushd "$CLONE"
+
+finish() {
+  printf "\n\n>>> exit status was %s\n" "$?"
+}
+trap finish EXIT
+
+nix-build -A test
+----
+
+We initially (lines #5 to #8) create a log file, named after _when_ the run is
+running and for _which_ commit it is running for.  The `exec` and `tee` combo
+allows the output of the script to go both to `stdout` _and_ the log file.  This
+makes the logs output show up when you do a `git push`.
+
+Lines #10 to #13 create a fresh clone of the repository and line #20 runs the
+test command.
+
+After using a similar post-receive hook for a while, I now even generate a
+simple HTML file to make the logs available ({example-project}[example project])
+through the browser.
+
+== Upsides
+
+No vendor lock-in, as all you need is a server with Nix installed.
+
+And if you pin the Nixpkgs version you're using, this very simple setup yields
+extremely sandboxed runs on a very hermetic environment.
+
+== Downsides
+
+Besides the many missing shiny features of this very simplistic CI, `nix-build`
+can be very resource intensive.  Specifically, it consumes too much memory.  So
+if it has to download too many things, or the build closure gets too big, the
+server might very well run out of memory.
diff --git a/src/content/en/tils/2020/11/12/git-bisect-automation.adoc b/src/content/en/tils/2020/11/12/git-bisect-automation.adoc
new file mode 100644
index 0000000..dff8737
--- /dev/null
+++ b/src/content/en/tils/2020/11/12/git-bisect-automation.adoc
@@ -0,0 +1,25 @@
+= Git bisect automation
+:categories: git
+:sort: 1
+
+It is good to have an standardized way to run builds and tests on the repository
+of a project, so that you can find when a bug was introduced by using
+`git bisect run`.
+
+I've already been in the situation when a bug was introduced and I didn't know
+how it even was occurring, and running Git bisect over hundreds of commits to
+pinpoint the failing commit was very empowering:
+
+[source,sh]
+----
+$ GOOD_COMMIT_SHA=e1fd0a817d192c5a5df72dd7422e36558fa78e46
+$ git bisect start HEAD $GOOD_COMMIT_SHA
+$ git bisect run sn -c './build.sh && ./run-failing-case.sh'
+----
+
+Git will than do a binary search between the commits, and run the commands you
+provide it with to find the failing commit.
+
+Instead of being afraid of doing a bisect, you should instead leverage it, and
+make Git help you dig through the history of the repository to find the bad
+code.
diff --git a/src/content/en/tils/2020/11/12/useful-bashvars.adoc b/src/content/en/tils/2020/11/12/useful-bashvars.adoc
new file mode 100644
index 0000000..fb148fb
--- /dev/null
+++ b/src/content/en/tils/2020/11/12/useful-bashvars.adoc
@@ -0,0 +1,61 @@
+= Useful Bash variables
+:categories: shell
+
+:bash:                   https://www.gnu.org/software/bash/
+:bash-bang-bang:         https://www.gnu.org/software/bash/manual/bash.html#Event-Designators
+:bash-dollar-underscore: https://www.gnu.org/software/bash/manual/bash.html#Special-Parameters
+
+{bash}[GNU Bash] has a few two letter variables that may be useful when typing
+on the terminal.
+
+== `!!`: the text of the last command
+
+The {bash-bang-bang}[`!!` variable] refers to the previous command, and I find
+useful when following chains for symlinks:
+
+[source,sh]
+----
+$ which git
+/run/current-system/sw/bin/git
+$ readlink $(!!)
+readlink $(which git)
+/nix/store/5bgr1xpm4m0r72h9049jbbhagxdyrnyb-git-2.28.0/bin/git
+----
+
+It is also useful when you forget to prefix `sudo` to a command that requires
+it:
+
+[source,sh]
+----
+$ requires-sudo.sh
+requires-sudo.sh: Permission denied
+$ sudo !!
+sudo ./requires-sudo.sh
+# all good
+----
+
+Bash prints the command expansion before executing it, so it is better for you
+to follow along what it is doing.
+
+== `$_`: most recent parameter
+
+The {bash-dollar-underscore}[`$_` variable] will give you the most recent
+parameter you provided to a previous argument, which can save you typing
+sometimes:
+
+[source,sh]
+----
+# instead of...
+$ mkdir -p a/b/c/d/
+$ cd a/b/c/d/
+
+# ...you can:
+$ mkdir -p a/b/c/d/
+$ cd $_
+----
+
+== Conclusion
+
+I wouldn't use those in a script, as it would make the script terser to read, I
+find those useful shortcut that are handy when writing at the interactive
+terminal.
diff --git a/src/content/en/tils/2020/11/14/gpodder-media.adoc b/src/content/en/tils/2020/11/14/gpodder-media.adoc
new file mode 100644
index 0000000..f722f35
--- /dev/null
+++ b/src/content/en/tils/2020/11/14/gpodder-media.adoc
@@ -0,0 +1,21 @@
+= gPodder as a media subscription manager
+
+:re-discover: https://www.charlieharrington.com/unexpected-useless-and-urgent
+:gpodder: https://gpodder.github.io/
+
+As we {re-discover}[re-discover] the value of Atom/RSS feeds, most useful feed
+clients I know of don't support media, specifically audio and video.
+
+{gpodder}[gPodder] does.
+
+It is mostly know as a desktop podcatcher.  But the thing about podcasts is that
+the feed is provided through an RSS/Atom feed.  So you can just use gPodder as
+your media feed client, where you have control of what you look at.
+
+I audio and video providers I know of offer an RSS/Atom view of their content,
+so you can, say, treat any YouTube channel like a feed on its own.
+
+gPodder will then managed your feeds, watched/unwatched, queue downloads, etc.
+
+Being obvious now, it was a big finding for me.  If it got you interested, I
+recommend you giving gPodder a try.
diff --git a/src/content/en/tils/2020/11/30/git-notes-ci.adoc b/src/content/en/tils/2020/11/30/git-notes-ci.adoc
new file mode 100644
index 0000000..48a996b
--- /dev/null
+++ b/src/content/en/tils/2020/11/30/git-notes-ci.adoc
@@ -0,0 +1,112 @@
+= Storing CI data on Git notes
+:categories: git ci
+
+:git-notes: https://git-scm.com/docs/git-notes
+:nix-bash-ci: link:../12/diy-nix-bash-ci.html
+:cgit: https://git.zx2c4.com/cgit/
+
+Extending the bare bones CI server I've {nix-bash-ci}[talked about before],
+divoplade on Freenode suggested storing CI artifacts on {git-notes}[Git notes],
+such as tarballs, binaries, logs, _etc_.
+
+I've written a small script that will put log files and CI job data on Git
+notes, and make it visible on the porcelain log.  It is a simple extension of
+the previous article:
+
+[source,sh]
+----
+#!/usr/bin/env bash
+set -Eeuo pipefail
+set -x
+
+PREFIX='/srv/ci/vps'
+mkdir -p "$PREFIX"
+read -r _ SHA _ # oldrev newrev refname
+FILENAME="$(date -Is)-$SHA.log"
+LOGFILE="$PREFIX/$FILENAME"
+exec &> >(tee -a "$LOGFILE")
+
+echo "Starting CI job at: $(date -Is)"
+
+finish() {
+  STATUS="$?"
+  printf "\n\n>>> exit status was %s\n" "$STATUS"
+  echo "Finishing CI job at: $(date -Is)"
+  popd
+  NOTE=$(cat <>> CI logs added as Git note."
+}
+trap finish EXIT
+
+unset GIT_DIR
+CLONE="$(mktemp -d)"
+git clone . "$CLONE"
+pushd "$CLONE"
+git config --global user.email git@euandre.org
+git config --global user.name 'EuAndreh CI'
+
+./container make check site
+./container make publish
+----
+
+The important part is in the `finish()` function: - #25 stores the exit status
+and the generated filename separated by spaces; - #26 adds the log file in a
+note using the `refs/notes/ci-logs` ref; - #27 it adds a note to the commit
+saying how to see the logs.
+
+A commit now has an attached note, and shows it whenever you look at it:
+
+[source,diff]
+----
+$ git show 87c57133abd8be5d7cc46afbf107f59b26066575
+commit 87c57133abd8be5d7cc46afbf107f59b26066575
+Author: EuAndreh 
+Date:   Wed Feb 24 21:58:28 2021 -0300
+
+    vps/machines.scm: Change path to cronjob files
+
+Notes:
+    See CI logs with:
+      git notes --ref=refs/notes/ci-logs show 87c57133abd8be5d7cc46afbf107f59b26066575
+      git notes --ref=refs/notes/ci-data show 87c57133abd8be5d7cc46afbf107f59b26066575
+
+diff --git a/servers/vps/machines.scm b/servers/vps/machines.scm
+index d1830ca..a4ccde7 100644
+--- a/servers/vps/machines.scm
++++ b/servers/vps/machines.scm
+@@ -262,8 +262,8 @@ pki " mail-domain " key  \"" (tls-priv-for mail-domain) "\""))
+             (service mcron-service-type
+                      (mcron-configuration
+                       (jobs
+-                       (list #~(job "30 1 * * 1" "guix gc -d")
+-                             #~(job "30 0 * * *" "/var/lib/euandreh/backup.sh")))))
++                       (list #~(job "30 1 * * 1" "/opt/bin/gc.sh")
++                             #~(job "30 0 * * *" "/opt/bin/backup.sh")))))
+             (service dhcp-client-service-type)
+             #;
+             (service opensmtpd-service-type
+----
+
+Other tools such as {cgit}[cgit] will also show notes on the web interface:
+https://euandre.org/git/servers/commit?id=87c57133abd8be5d7cc46afbf107f59b26066575.
+
+You can go even further: since cgit can serve raw blob directly, you can even
+serve such artifacts (log files, release artifacts, binaries) from cgit itself:
+
+[source,sh]
+----
+$ SHA="$(git notes --ref=refs/notes/ci-logs list 87c57133abd8be5d7cc46afbf107f59b26066575)"
+$ echo "https://euandre.org/git/servers/blob?id=$SHA"
+https://euandre.org/git/servers/blob?id=1707a97bae24e3864fe7943f8dda6d01c294fb5c
+----
+
+And like that you'll have cgit serving the artifacts for you:
+https://euandre.org/git/servers/blob?id=1707a97bae24e3864fe7943f8dda6d01c294fb5c.
diff --git a/src/content/en/tils/2020/12/15/shellcheck-repo.adoc b/src/content/en/tils/2020/12/15/shellcheck-repo.adoc
new file mode 100644
index 0000000..387e793
--- /dev/null
+++ b/src/content/en/tils/2020/12/15/shellcheck-repo.adoc
@@ -0,0 +1,165 @@
+= Awk snippet: ShellCheck all scripts in a repository
+:categories: shell
+:updatedat: 2020-12-16
+
+:awk-20-min: https://ferd.ca/awk-in-20-minutes.html
+:shellcheck: https://www.shellcheck.net/
+
+Inspired by Fred Herbert's "{awk-20-min}[Awk in 20 Minutes]", here's a problem I
+just solved with a line of Awk: run ShellCheck in all scripts of a repository.
+
+In my repositories I usually have Bash and POSIX scripts, which I want to keep
+tidy with {shellcheck}[ShellCheck].  Here's the first version of
+`assert-shellcheck.sh`:
+
+[source,sh]
+----
+#!/bin/sh -eux
+
+find . -type f -name '*.sh' -print0 | xargs -0 shellcheck
+----
+
+This is the type of script that I copy around to all repositories, and I want it
+to be capable of working on any repository, without requiring a list of files to
+run ShellCheck on.
+
+This first version worked fine, as all my scripts had the `.sh' ending.  But I
+recently added some scripts without any extension, so `assert-shellcheck.sh`
+called for a second version.  The first attempt was to try grepping the shebang
+line:
+
+[source,sh]
+----
+$ grep '^#!/' assert-shellcheck.sh
+#!/usr/sh
+----
+
+Good, we have a grep pattern on the first try.  Let's try to find all the
+matching files:
+
+[source,sh]
+----
+$ find . -type f | xargs grep -l '^#!/'
+./TODOs.org
+./.git/hooks/pre-commit.sample
+./.git/hooks/pre-push.sample
+./.git/hooks/pre-merge-commit.sample
+./.git/hooks/fsmonitor-watchman.sample
+./.git/hooks/pre-applypatch.sample
+./.git/hooks/pre-push
+./.git/hooks/prepare-commit-msg.sample
+./.git/hooks/commit-msg.sample
+./.git/hooks/post-update.sample
+./.git/hooks/pre-receive.sample
+./.git/hooks/applypatch-msg.sample
+./.git/hooks/pre-rebase.sample
+./.git/hooks/update.sample
+./build-aux/with-guile-env.in
+./build-aux/test-driver
+./build-aux/missing
+./build-aux/install-sh
+./build-aux/install-sh~
+./bootstrap
+./scripts/assert-todos.sh
+./scripts/songbooks
+./scripts/compile-readme.sh
+./scripts/ci-build.sh
+./scripts/generate-tasks-and-bugs.sh
+./scripts/songbooks.in
+./scripts/with-container.sh
+./scripts/assert-shellcheck.sh
+----
+
+This approach has a problem, though: it includes files ignored by Git, such as
+`builld-aux/install-sh~`, and even goes into the `.git/` directory and finds
+sample hooks in `.git/hooks/*`.
+
+To list the files that Git is tracking we'll try `git ls-files`:
+
+[source,sh]
+----
+$ git ls-files | xargs grep -l '^#!/'
+TODOs.org
+bootstrap
+build-aux/with-guile-env.in
+old/scripts/assert-docs-spelling.sh
+old/scripts/build-site.sh
+old/scripts/builder.bats.sh
+scripts/assert-shellcheck.sh
+scripts/assert-todos.sh
+scripts/ci-build.sh
+scripts/compile-readme.sh
+scripts/generate-tasks-and-bugs.sh
+scripts/songbooks.in
+scripts/with-container.sh
+----
+
+It looks to be almost there, but the `TODOs.org` entry shows a flaw in it: grep
+is looking for a +'^#!/'+ pattern on any part of the file.  In my case,
+`TODOs.org` had a snippet in the middle of the file where a line started with
++#!/bin/sh+.
+
+So what we actually want is to match the *first* line against the pattern.  We
+could loop through each file, get the first line with `head -n 1` and grep
+against that, but this is starting to look messy.  I bet there is another way of
+doing it concisely...
+
+Let's try Awk.  I need a way to select the line numbers to replace `head -n 1`,
+and to stop processing the file if the pattern matches.  A quick search points
+me to using `FNR` for the former, and `{ nextline }` for the latter.  Let's try
+it:
+
+[source,sh]
+----
+$ git ls-files | xargs awk 'FNR>1 { nextfile } /^#!\// { print FILENAME; nextfile }'
+bootstrap
+build-aux/with-guile-env.in
+old/scripts/assert-docs-spelling.sh
+old/scripts/build-site.sh
+old/scripts/builder.bats.sh
+scripts/assert-shellcheck.sh
+scripts/assert-todos.sh
+scripts/ci-build.sh
+scripts/compile-readme.sh
+scripts/generate-tasks-and-bugs.sh
+scripts/songbooks.in
+scripts/with-container.sh
+----
+
+Great!  Only `TODOs.org` is missing, but the script is much better: instead of
+matching against any part of the file that may have a shebang-like line, we only
+look for the first.  Let's put it back into the `assert-shellcheck.sh` file and
+use `NULL` for separators to accommodate files with spaces in the name:
+
+[source,sh]
+----
+#!/usr/sh -eux
+
+git ls-files -z | \
+  xargs -0 awk 'FNR>1 { nextfile } /^#!\// { print FILENAME; nextfile }' | \
+  xargs shellcheck
+----
+
+This is where I've stopped, but I imagine a likely improvement: match against
+only +#!/bin/sh+ and +#!/usr/bin/env bash+ shebangs (the ones I use most), to
+avoid running ShellCheck on Perl files, or other shebangs.
+
+Also when reviewing the text of this article, I found that `{ nextfile }` is a
+GNU Awk extension.  It would be an improvement if `assert-shellcheck.sh` relied
+on the POSIX subset of Awk for working correctly.
+
+== _Update_
+
+After publishing, I could remove `{ nextfile }` and even make the script
+simpler:
+
+[source,sh]
+----
+#!/usr/sh -eux
+
+git ls-files -z | \
+  xargs -0 awk 'FNR==1 && /^#!\// { print FILENAME }' | \
+  xargs shellcheck
+----
+
+Now both the shell and Awk usage are POSIX compatible.
diff --git a/src/content/en/tils/2020/12/29/svg.adoc b/src/content/en/tils/2020/12/29/svg.adoc
new file mode 100644
index 0000000..0e5dec3
--- /dev/null
+++ b/src/content/en/tils/2020/12/29/svg.adoc
@@ -0,0 +1,125 @@
+= SVG favicon
+:updatedat: 2021-01-12
+
+:favicon: link:../../../../img/favicon.svg
+
+I've wanted to change this website's favicon from a plain `.ico` file to a
+proper SVG.  The problem I was trying to solve was to reuse the same image on
+other places, such as avatars.
+
+Generating a PNG from the existing 16x16 icon was possible but bad: the final
+image was blurry.  Converting the `.ico` to an SVG was possible, but
+sub-optimal: tools try to guess some vector paths, and the final SVG didn't
+match the original.
+
+Instead I used a tool to draw the "vector pixels" as black squares, and after
+getting the final result I manually cleaned-up the generated XML:
+
+[source,xml]
+----
+
+
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+  
+
+----
+
+The good thing about this new favicon (at {favicon}[`/static/lord-favicon.svg`])
+is that a) it is simple enough that I feel comfortable editing it manually and
+b) it is an SVG, which means I can generate any desired size.
+
+With the new favicon file, I now had to add to the templates' `` a
+`` to this icon:
+
+[source,html]
+----
+
+  
+  
+  ...
+----
+
+Still missing is a bitmap image for places that can't handle vector images.  I
+used Jekyll generator to create an PNG from the existing SVG:
+
+[source,ruby]
+----
+module Jekyll
+  class FaviconGenerator < Generator
+    safe true
+    priority :high
+
+    SIZE = 420
+
+    def generate(site)
+      svg = 'static/favicon.svg'
+      png = 'static/favicon.png'
+      unless File.exist? png then
+        puts "Missing '#{png}', generating..."
+        puts `inkscape -o #{png} -w #{SIZE} -h #{SIZE} #{svg}`
+      end
+    end
+  end
+end
+----
+
+I had to increase the priority of the generator so that it would run before
+other places that would use a `{% link /static/lord-favicon.png %}`, otherwise
+the file would be considered missing.
-- 
cgit v1.2.3