EXJ(1)
exj
NAME
exj - node.js standard input processor
SYNOPSIS
exj [OPTIONS] 'fn'
exj [OPTIONS] -f | --file 'fnfile'
DESCRIPTION
Exj executes the given fn upon the standard input. Fn is expected to
be a JavaScript function expression. The result of fn execution is
printed to standard output.
If the result type of fn is a string, the result is printed directly
to standard output.
If the result type of fn is null or undefined, no action is taken.
Any other result type is converted to JSON using JSON.stringify() and
pretty-printed to standard output.
If the result of fn is a Promise, the promise will be resolved and the
result printed according to the above rules.
GLOBALS
EXEC
A tagged template string which will execute escape and execute the contents as a child
process, similar to running with -x
EXAMPLE - print all files in the current directory:
echo ls | exj -l 'x => EXEC`cat ${x}`'
OPTIONS
-j, --json
Treat the input text as JSON. Input text will be parsed to
JavaScript objects using JSON.parse() before being passed to fn.
-p, --pretty
Pretty print JSON output
-l, --line
Process each line of input separately. For each line of standard
input, fn will be invoked for each line encountered, and the
result will be written to standard output.
-x, --exec
Execute each output entry as a child process. The standard output
of the finished process will be written to standard out.
NOTE: Output entry MUST be an array of the format ['executable', 'arg1', 'arg2', ...]
-f, --file 'fnfile'
Read fn from a file, whose path is located at 'fnfile'.
-g, --group-lines 'num'
When processing lines, group batches of num lines together as an array
-c, --concurrency 'num'
When executing results via --exec option, execute at most num
commands at once.
Concurrency level also applies to awaiting of Promise results: no more lines
of input will be processed while 'num' results are in flight.
-r, --require package[:alias]
An NPM package to be required into the namespace of 'fn', with optional alias
--help
Print usage text
EXAMPLES
ls | exj -l 'x => x.toUpperCase()'
Print the contents of the current directory in uppercase
curl https://jsonplaceholder.typicode.com/photos \
| exj -j 'res => res.map((image) => `${image.title} - ${image.thumbnailUrl}`).join("\n")' | pbcopy
Fetch and process a JSON payload of album artwork to the clipboard
ls *.js | exj -lx 'x => ["mv", x, x.replace(/\.js$/, ".ts")]'
convert javascript files to typescript
cat urls.txt -l --concurrency 5 --require 'node-fetch:fetch' 'url => fetch(url).then(r => r.json())'
Fetch the json contents of a list of URLs, fetching up to five URLs simultaneously
SEE ALSO
awk(1), jq(1), xargs(1)