Add another TIL on AWK: curl flags

1 files changed, 243 insertions, 0 deletions

diff --git a/locale/pt/LC_MESSAGES/_tils/2021-01-12-awk-snippet-send-email-to-multiple-recipients-with-curl.po b/locale/pt/LC_MESSAGES/_tils/2021-01-12-awk-snippet-send-email-to-multiple-recipients-with-curl.po
new file mode 100644
index 0000000..7561292
--- /dev/null
+++ b/locale/pt/LC_MESSAGES/_tils/2021-01-12-awk-snippet-send-email-to-multiple-recipients-with-curl.po
@@ -0,0 +1,243 @@
+#
+msgid ""
+msgstr ""
+
+msgid "title: 'Awk snippet: send email to multiple recipients with cURL'"
+msgstr ""
+
+msgid "date: 2021-01-12"
+msgstr ""
+
+msgid "layout: post"
+msgstr ""
+
+msgid "lang: en"
+msgstr ""
+
+msgid "ref: awk-snippet-send-email-to-multiple-recipients-with-curl"
+msgstr ""
+
+msgid "My requirements for the `sendmail` command were:"
+msgstr ""
+
+msgid "store the email in a file, and send it later."
+msgstr ""
+
+msgid "send from different addresses, using different SMTP servers;"
+msgstr ""
+
+msgid ""
+"I couldn't find an MTA that could accomplish that, but I was able to quickly"
+" write a solution."
+msgstr ""
+
+msgid "The first part was the easiest: store the email in a file:"
+msgstr ""
+
+msgid ""
+"# ~/.config/mutt/muttrc:\n"
+"set sendmail=~/bin/enqueue-email.sh\n"
+"\n"
+"# ~/bin/enqueue-email.sh:\n"
+"#!/bin/sh -eu\n"
+"\n"
+"cat - > \"$HOME/mbsync/my-queued-emails/$(date -Is)\"\n"
+msgstr ""
+
+msgid ""
+"Now that I had the email file store locally, I needed a program to send the "
+"email from the file, so that I could create a cronjob like:"
+msgstr ""
+
+msgid ""
+"for f in ~/mbsync/my-queued-emails/*; do\n"
+"  ~/bin/dispatch-email.sh \"$f\" && rm \"$f\"\n"
+"done\n"
+msgstr ""
+
+msgid ""
+"The `dispatch-email.sh` would have to look at the `From: ` header and decide"
+" which SMTP server to use. As I [found "
+"out](https://blog.edmdesigner.com/send-email-from-linux-command-line/) that "
+"[curl](https://curl.se/) supports SMTP and is able to send emails, this is "
+"what I ended up with:"
+msgstr ""
+
+msgid "Most of curl flags used are self-explanatory, except for `$rcpt`."
+msgstr ""
+
+msgid ""
+"curl connects to the SMTP server, but doesn't set the recipient address by "
+"looking at the message. My solution was to generate the curl flags, store "
+"them in `$rcpt` and use it unquoted to leverage shell word splitting."
+msgstr ""
+
+msgid ""
+"To me, the most interesting part was building the `$rcpt` flags. My first "
+"instinct was to try grep, but it couldn't print only matches in a regex. As "
+"I started to turn towards sed, I envisioned needing something else to loop "
+"over the sed output, and I then moved to Awk."
+msgstr ""
+
+msgid ""
+"$ H='To: to@example.com, to2@example.com\\nCc: cc@example.com, cc2@example.com\\nBcc: bcc@example.com,bcc2@example.com\\n'\n"
+"$ printf \"$H\" | awk '/^To: .*$/ { print $0 }'\n"
+"To: to@example.com, to2@example.com\n"
+"$ printf \"$H\" | awk 'match($0, /^To: (.*)$/, m) { print m }'\n"
+"awk: ligne de commande:1: (FILENAME=- FNR=1) fatal : tentative d'utilisation du tableau « m » dans un contexte scalaire\n"
+"$ printf \"$H\" | awk 'match($0, /^To: (.*)$/, m) { print m[0] }'\n"
+"To: to@example.com, to2@example.com\n"
+"$ printf \"$H\" | awk 'match($0, /^To: (.*)$/, m) { print m[1] }'\n"
+"to@example.com, to2@example.com\n"
+"$ printf \"$H\" | awk 'match($0, /^To: (.*)$/, m) { split(m[1], tos, \" \"); print tos }'\n"
+"awk: ligne de commande:1: (FILENAME=- FNR=1) fatal : tentative d'utilisation du tableau « tos » dans un contexte scalaire\n"
+"$ printf \"$H\" | awk 'match($0, /^To: (.*)$/, m) { split(m[1], tos, \" \"); print tos[0] }'\n"
+"\n"
+"$ printf \"$H\" | awk 'match($0, /^To: (.*)$/, m) { split(m[1], tos, \" \"); print tos[1] }'\n"
+"to@example.com,\n"
+"$ printf \"$H\" | awk 'match($0, /^To: (.*)$/, m) { split(m[1], tos, \" \"); print tos[2] }'\n"
+"to2@example.com\n"
+"$ printf \"$H\" | awk 'match($0, /^To: (.*)$/, m) { split(m[1], tos, \" \"); print tos[3] }'\n"
+"\n"
+msgstr ""
+
+msgid ""
+"(This isn't the verbatim interactive session, but a cleaned version to make "
+"it more readable.)"
+msgstr ""
+
+msgid ""
+"At this point, I realized I needed a for loop over the `tos` array, and I "
+"moved the Awk snippet into the `~/bin/dispatch-email.sh`. I liked the final "
+"thing:"
+msgstr ""
+
+msgid ""
+"match($0, /^(To|Cc|Bcc): (.*)$/, m) {\n"
+"  split(m[2], tos, \",\")\n"
+"  for (i in tos) {\n"
+"    print \"--mail-rcpt \" tos[i]\n"
+"  }\n"
+"}\n"
+msgstr ""
+
+msgid ""
+"As I learn more about Awk, I feel that it is too undervalued, as many people"
+" turn to Perl or other programming languages when Awk suffices. The "
+"advantage is pretty clear: writing programs that run on any POSIX system, "
+"without extra dependencies required."
+msgstr ""
+
+msgid "Coding to the standards is underrated."
+msgstr ""
+
+msgid ""
+"#!/bin/sh -eu\n"
+"\n"
+"F=\"$1\"\n"
+"\n"
+"rcpt=\"$(awk '\n"
+"  match($0, /^(To|Cc|Bcc): (.*)$/, m) {\n"
+"    split(m[2], tos, \",\")\n"
+"    for (i in tos) {\n"
+"      print \"--mail-rcpt \" tos[i]\n"
+"    }\n"
+"  }\n"
+"'  \"$F\")\"\n"
+"\n"
+"if grep -qE '^From: .*<addr@server1\\.org>$' \"$F\"; then\n"
+"  curl                                                      \\\n"
+"    -s                                                      \\\n"
+"    --url smtp://smtp.server1.org:587                       \\\n"
+"    --ssl-reqd                                              \\\n"
+"    --mail-from addr@server1.org                            \\\n"
+"    $rcpt                                                   \\\n"
+"    --user 'addr@server1.org:my-long-and-secure-passphrase' \\\n"
+"    --upload-file \"$F\"\n"
+"elif grep -qE '^From: .*<addr@server2\\.org>$' \"$F\"; then\n"
+"  curl                                                      \\\n"
+"    -s                                                      \\\n"
+"    --url smtp://smtp.server2.org:587                       \\\n"
+"    --ssl-reqd                                              \\\n"
+"    --mail-from addr@server2.org                            \\\n"
+"    $rcpt                                                   \\\n"
+"    --user 'addr@server2.org:my-long-and-secure-passphrase' \\\n"
+"    --upload-file \"$F\"\n"
+"else\n"
+"  echo 'Bad \"From: \" address'\n"
+"  exit 1\n"
+"fi\n"
+msgstr ""
+
+msgid ""
+"As I experimented with [Neomutt](https://neomutt.org/), I wanted to keep "
+"being able to enqueue emails for sending later like my previous setup, so "
+"that I didn't rely on having an internet connection."
+msgstr ""
+
+msgid ""
+"In the short Awk snippet, 3 things were new to me: the `match(...)`, "
+"`split(...)` and `for () {}`. The only other function I have ever used was "
+"`gsub(...)`, but these new ones felt similar enough that I could almost "
+"guess their behaviour and arguments. `match(...)` stores the matches of a "
+"regex on the given array positionally, and `split(...)` stores the chunks in"
+" the given array."
+msgstr ""
+
+msgid "I even did it incrementally:"
+msgstr ""
+
+#~ msgid "I even did this incrementally:"
+#~ msgstr ""
+
+#~ msgid ""
+#~ "In the short Awk snippet, 3 things were new to me: the `match(...)`, "
+#~ "`split(...)` and `for () {}`. The only other function I have ever used was "
+#~ "`gsub(...)`, but these new felt similar enough that I could almost guess "
+#~ "their behaviour. `match(...)` stores the matches of a regex on the given "
+#~ "array positionally, and `split(...)` stores the chunks in the given array."
+#~ msgstr ""
+
+#~ msgid ""
+#~ "As I experimented with [Neomutt](https://neomutt.org/), I wanted to keep "
+#~ "being able to enqueue emails for sending later, so that I didn't rely on "
+#~ "having an internet connection."
+#~ msgstr ""
+
+#~ msgid ""
+#~ "#!/bin/sh -eu\n"
+#~ "\n"
+#~ "F=\"$1\"\n"
+#~ "\n"
+#~ "rcpt=\"$(awk '\n"
+#~ "  match($0, /^(To|Cc|Bcc): (.*)$/, m) {\n"
+#~ "    split(m[2], tos, \",\")\n"
+#~ "    for (i in tos) {\n"
+#~ "      print \"--mail-rcpt \" tos[i]\n"
+#~ "    }\n"
+#~ "  }\n"
+#~ "'  \"$F\")\"\n"
+#~ "\n"
+#~ "if grep -qE '^From: .*<addr@server1\\.org>$' \"$F\"; then\n"
+#~ "  curl                                                      \\\n"
+#~ "    -s                                                      \\\n"
+#~ "    --url smtp://smtp.server1.org:587                       \\\n"
+#~ "    --ssl-reqd                                              \\\n"
+#~ "    --mail-from addr@server1.org                            \\\n"
+#~ "    $rcpt                                                   \\\n"
+#~ "    --user 'addr@server1.org:my-long-and-secure-passphrase' \\\n"
+#~ "    --upload-file \"$F\"\n"
+#~ "eliif grep -qE '^From: .*<addr@server2\\.org>$' \"$F\"; then\n"
+#~ "  curl                                                      \\\n"
+#~ "    -s                                                      \\\n"
+#~ "    --url smtp://smtp.server2.org:587                       \\\n"
+#~ "    --ssl-reqd                                              \\\n"
+#~ "    --mail-from addr@server2.org                            \\\n"
+#~ "    $rcpt                                                   \\\n"
+#~ "    --user 'addr@server2.org:my-long-and-secure-passphrase' \\\n"
+#~ "    --upload-file \"$F\"\n"
+#~ "else\n"
+#~ "  echo 'Bad \"From: \" address'\n"
+#~ "  exit 1\n"
+#~ "fi\n"
+#~ msgstr ""