docs: add gh-actions, bash, curl (#35)

bash/2023-08-24-bash-declare-and-loop-over-array.md

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+---
+title:  'Bash - declare and loop over array'
+author: julius
+date: '2023-08-24T19:05:00:00+01:00'
+tags:
+  - 'bash'
+---
+
+How to declare an array and loop over it?
+
+```bash
+# declare array: https://www.gnu.org/software/bash/manual/html_node/Arrays.html
+declare -a myArray=("Linux Mint" "Fedora" "Red Hat Linux" "Ubuntu" "Debian" )
+
+# loop through it: https://www.freecodecamp.org/news/bash-array-how-to-declare-an-array-of-strings-in-a-bash-script/
+for str in ${myArray[@]}; do
+  echo $str
+done
+```
+
+Sources:
+
+- declare array: https://www.gnu.org/software/bash/manual/html_node/Arrays.html
+- loop through an array: https://www.freecodecamp.org/news/bash-array-how-to-declare-an-array-of-strings-in-a-bash-script/

bash/2023-08-24-bash-pass-variables-to-curl-data.md

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+---
+title:  'Bash and curl - pass variables to curl'
+author: julius
+date: '2023-08-24T19:05:00:00+01:00'
+tags:
+  - 'curl'
+  - 'bash'
+---
+
+I often call `curl` in a `bash` script.
+How do I pass variables that I've set in `bash` as arguments to `curl`'s command line option, say `--data`?
+
+Below is an example without variables.
+
+```bash
+curl \
+  --header "Content-Type: application/json" \
+  --data '{
+            "name": "Hello John Doe" 
+          }' \
+  http://example.com
+```
+
+Splitting `John Doe` into two variables, and passing them to `curl` makes the server display the `greeting` as `"Hello $firstname $lastname"`.
+
+```bash
+# with variable - doesn't work. Variables are sent in request as is.
+# Server displays "Hello $firstname $lastname"
+$firstname="John"
+$lastname="Doe"
+
+curl \
+  --header "Content-Type: application/json" \
+  --data '{
+            "greeting": "Hello $firstname $lastname",
+            "firstname": "$firstname",
+            "lastname": "$lastname",
+          }' \
+  http://example.com
+```
+
+I've come across two cases:
+
+- If a variable is part of an already in a double quoted string, enclose in single quotes. 
+See the value of key, `greeting`.
+- if a variable is to be its own json value, escape the double quotes. See `greeting`. 
+See the value of key, `firstname` and `lastname`
+
+```bash
+$firstname="John"
+$lastname="Doe"
+
+curl \
+  --header "Content-Type: application/json" \
+  --data '{
+            "greeting": "Hello '$firstname' '$lastname'",
+            "firstname": '\"$firstname\"',
+            "lastname": '\"$lastname\"'
+          }' \
+  http://example.com
+```
+
+Thanks to [ Bernie Michalik's post](https://smartpeopleiknow.com/2021/11/12/if-you-are-writing-a-bash-script-to-call-a-curl-command-and-you-want-to-pass-variable-values-to-it-read-this) for the hints.

bash/2023-08-24-bash-save-curl-response-code-and-body-in-variable.md

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+---
+title:  'Bash - save curl response code and body in variables'
+author: julius
+date: '2023-08-24T19:05:00:00+01:00'
+tags:
+  - 'curl'
+  - 'bash'
+---
+
+Save curl httpcode and response in variables for further processing.
+Found via https://unix.stackexchange.com/a/572434
+
+```bash
+#!/bin/bash
+
+URL="https://example.com"
+
+response=$(curl --silent --write-out "%{http_code}" $URL)
+
+http_code=$(tail -n1 <<< "$response")  # get the last line
+content=$(sed '$ d' <<< "$response")   # get all but the last line which contains the status code
+
+echo "$http_code"
+echo "$content"
+
+# do something with the http_code, such as
+if [[ "http_code" -ne 201 ]]; then
+    echo "Create failed."
+    exit 1
+fi
+```
+
+Links to the command line options:
+
+- [`-s, --silent`](https://curl.se/docs/manpage.html#-s)
+- [`-w, --write-out`](https://curl.se/docs/manpage.html#-w)

github-actions/pass-list-var-to-bash-for-loop.md

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+# Pass list to bash for processing
+
+Set list in a GitHub Actions workflow.
+And pass it to bash for processing, such as [looping through it](../bash/2023-08-24-bash-declare-and-loop-over-array.md).
+
+```yml
+name: my workflow
+on:
+  workflow_dispatch:
+  . . .
+  jobs:
+    jobA:
+      # . . .
+      steps:
+        - name: Print List
+          env:
+            MY_LIST: '"a","b","c"'
+          run: |
+            bash .github/scripts/print-list.sh
+          shell: bash
+```
+
+Then, in bash, loop over the list and do something with it.
+
+```bash
+#!/bin/bash
+
+# file: .github/scripts/print-list.sh
+
+# check that env vars have been set
+if [[ -z "${MY_LIST:-}" ]]; then
+	echo "ERROR: Missing env var MY_LIST"
+exit 1
+fi
+
+# string processing via https://stackoverflow.com/a/35894538
+for i in ${MY_LIST//,/ }
+do
+    echo "$i"
+    # remove first and last quotes: https://stackoverflow.com/a/9733456
+    i_without_quotes=$(sed -e 's/^"//' -e 's/"$//' <<<"$i")
+
+    echo "$i"
+done
+```