We’ve all been there. I ran command x, and now I want to run it in the context of command y but I’m dealing with nested strings and it’s a pain. I use this method to quickly avoid all the shell nonsense and escaping. I like to keep my snippets terse, so comments will be inline.

# This creates a method that will read lines into a variable. There's probably a limitation on bash versions, so this may not work on older systems.

define(){ IFS='\n' read -r -d '' ${1} || true; }

# Given jq, a popular cli json manipulator lets select the animal dog
# {
#   "animals": [
#     {
#       "animal": "dog"
#     },
#     {
#       "animal": "cat"
#     }
#   ]
# }

ANIMAL=dog

define JQ_COMMAND <<EOF
jq -r '.animals[] | select( .animal | contains("$ANIMAL"))'
EOF

# Then, with the previous json object in my paste buffer, we'll simple eval this command

pbpaste | eval $JQ_COMMAND
# Output:
# {
#  "animal": "dog"
# }

# This example is contrived, but jq has wonkey stuff going on with quoting and sub quoting because it has its own interpreter. Since we create a here doc, we can pre-interpolate variables and then execute the whole command in line.