chem

Repeating yourself on the command line, but not enough to write a shell script?

chem can help.

$ chem help
NAME
    chem - chem is a tool for list manipulation and shell automation

SYNOPSIS
    chem [global options] command [command options] [arguments...]

VERSION
    1.0.0

GLOBAL OPTIONS
    --help        - Show this message
    --verbose, -V - Display verbose output
    --version     - Display the program version

COMMANDS
    drop   - Delete a collection
    edit   - Edit a collection in vi
    exec   - Execute a command or set of commands with substitution (use quotes)
    help   - Shows a list of commands or help for one command
    in     - Create or modify a collection with data from stdin
    init   - Create an empty .chemrc file
    list   - List all collections
    new    - Create an empty collection
    out    - Show the contents of a collection
    rename - Rename a collection
    run    - Execute a collection as a list of commands with substitution
    run1   - Execute a single command from a collection with substitution
    runN   - Execute a collection's Nth set of commands with substitution

Installation

chem is written in Ruby.

git clone git@github.com:modality/chem.git
cd chem
bundle install --path vendor/bundle
rake install

Create a workspace: init

Create a new .chemrc file in the current directory to use chem.

$ chem init
Initialized empty .chemrc file at ~/.chemrc

Piping: in and out

Pipe to and from chem.

$ echo -e "12\n23\n34" | chem in foo
Added new collection "foo"

$ chem out foo
12
23
34

$ chem out foo | grep 2
12
23

Execution: exec, run, run1, and runN

Now for some advanced substitution techniques. These commands execute in the context of the current .chemrc file. Text with angle brackets will be replaced with values from that collection.

Let's set up some test data to play with.

$ echo -e "chem\ngem\ngarbage" | chem in vals && chem out vals
Added new collection "vals"
chem
gem
garbage

$ echo -e "echo \"filenames containing <vals>\"\n\
ls -al | grep -i <vals>" | chem in val_user
Added new collection "val_user"

$ chem out val_user
echo "filenames containing <vals>"
ls -al | grep -i <vals>

exec - Execute commands from the command line

$ chem exec "echo 0 <vals>" "echo 1 <vals>"
0 chem
1 chem
0 gem
1 gem
0 garbage
1 garbage

run - Execute a collection

$ chem run val_user
filenames containing chem
-rw-r--r--   1 michaelhansen  staff   743 Jan 25 20:06 .chemrc
-rw-r--r--   1 michaelhansen  staff   713 Jan 25 19:31 chem.gemspec
filenames containing gem
-rw-r--r--   1 michaelhansen  staff    38 Jan  9 08:35 Gemfile
-rw-r--r--   1 michaelhansen  staff  1074 Jan 24 15:29 Gemfile.lock
-rw-r--r--   1 michaelhansen  staff   713 Jan 25 19:31 chem.gemspec
filenames containing garbage

run1 - Execute a single line in a collection as a command

$ chem -V out val_user
id | value
0  | echo "filenames containing <vals>"
1  | ls -al | grep -i <vals>

$ chem run1 val_user 0
filenames containing chem
filenames containing gem
filenames containing garbage

runN - Execute a collection of commands, using the Nth substitution

$ chem -V out vals
id | value
0  | chem
1  | gem
2  | garbage

$ chem runN val_user 1
filenames containing gem
-rw-r--r--   1 michaelhansen  staff    38 Jan  9 08:35 Gemfile
-rw-r--r--   1 michaelhansen  staff  1074 Jan 24 15:29 Gemfile.lock
-rw-r--r--   1 michaelhansen  staff   713 Jan 25 19:31 chem.gemspec