YumaInaura/..SUBCOMMAND.md

## ..SUBCOMMAND.md

      
    Raw
  

              ..SUBCOMMAND.md
            
          
    It is just string assignment
So subcommand is not executed in this line's timing
echo_random_command_as_string='echo $((RANDOM))' 
When not use eval, just echo string
$echo_random_command_as_string # $((RANDOM))
Eval : execute command from string
These lines execute echo $((RANDOM)) everytime
eval $echo_random_command_as_string  # e.g 76811 : randomized every time
eval $echo_random_command_as_string  # e.g 345   : randomized every time
eval $echo_random_command_as_string  # e.g 6532  : randomized every time
This is a wrong case ( not exepected result )
Subcommand is executed immediately when assignment
So variable got fixed string like 'echo 3457'
echo_random_fixed="echo $((RANDOM))"

$echo_random_fixed # e.g 3457 : not randomized every time
$echo_random_fixed # e.g 3457 : not randomized every time
$echo_random_fixed # e.g 3457 : not randomized every time

  
## ..UNDERSTAND.md

      
    Raw
  

              ..UNDERSTAND.md
            
          
    Shell—Understanding eval behaviour ( with random command example )


#!/bin/bash -eu

echo_alice_and_bob='echo alice; echo bob'

$echo_alice_and_bob       # alice; echo bob
eval $echo_alice_and_bob  # alice # bob


echo_carol_and_david='echo carol && echo david'

$echo_carol_and_david       # bob && echo carol
eval $echo_carol_and_david  # bob # carol

$echo_alice_and_bob $echo_carol_and_david       # alice; echo bob echo carol && echo david
eval $echo_alice_and_bob $echo_carol_and_david  # alice # bob echo carol
Variable (parameter) substitution happens as shell syntax

It is not special for eval command.
echo=echo
ok=ok

eval "$echo" "$ok" # ok
echo=echo
ok=ok
eval=eval

"$eval" "$echo" "$ok" # ok

  
## .dockerignore
docker.sh

## .gist.url
https://gist.github.com/YumaInaura/838cac70898062585f90206861ccb7e9

## command_combination.sh
#!/bin/bash -eu

echo_alice_and_bob='echo alice; echo bob'

$echo_alice_and_bob       # alice; echo bob
eval $echo_alice_and_bob  # alice # bob


echo_carol_and_david='echo carol && echo david'

$echo_carol_and_david       # bob && echo carol
eval $echo_carol_and_david  # bob # carol

$echo_alice_and_bob $echo_carol_and_david       # alice; echo bob echo carol && echo david
eval $echo_alice_and_bob $echo_carol_and_david  # alice # bob echo carol

## command_combination.sh.log
+ echo_alice_and_bob='echo alice; echo bob'
+ echo 'alice;' echo bob
alice; echo bob
+ eval echo 'alice;' echo bob
++ echo alice
alice
++ echo bob
bob
+ echo_carol_and_david='echo carol && echo david'
+ echo carol '&&' echo david
carol && echo david
+ eval echo carol '&&' echo david
++ echo carol
carol
++ echo david
david
+ echo 'alice;' echo bob echo carol '&&' echo david
alice; echo bob echo carol && echo david
+ eval echo 'alice;' echo bob echo carol '&&' echo david
++ echo alice
alice
++ echo bob echo carol
bob echo carol
++ echo david
david

## convert_test.sh
#!/bin/bash

# comment
# commnnt

code
code

# comment

code
code # codecomment
code


## docker.sh
#!/bin/bash

docker build . -t shell_eval
docker run shell_eval ./run.sh


## Dockerfile
FROM ubuntu

WORKDIR /script
COPY ./ /script

## expected.sh
#!/bin/bash -eux

# Assignment as just string
command='$((RANDOM))'

# It works
# It is equivalent to execute command `echo $((RANDOM))` every times
eval echo "$command" # e.g. 34641
eval echo $command   # e.g. 755
eval "echo $command" # e.g. 1235

# Assignment as just string
command='$((RANDOM))'

# It works
# It is equivalent to execute command `echo $((RANDOM))` every times
eval echo "$command" # e.g. 27571
eval echo $command   # e.g. 2435
eval "echo $command" # e.g. 2435


## expected.sh.log
+ command='$((RANDOM))'
+ eval echo '$((RANDOM))'
++ echo 30720
30720
+ eval echo '$((RANDOM))'
++ echo 10733
10733
+ eval 'echo $((RANDOM))'
++ echo 7850
7850
+ command='$((RANDOM))'
+ eval echo '$((RANDOM))'
++ echo 22658
22658
+ eval echo '$((RANDOM))'
++ echo 24486
24486
+ eval 'echo $((RANDOM))'
++ echo 32756
32756

## files_to_markdown.rb
#!/usr/bin/env ruby

STDOUT.sync = true

input_file_path = ARGV[0] || (raise 'Please specify file path in command first argument')
output_file_path = ARGV[1] || input_file_path

debug_mode = !!ARGV.detect { |argv| argv == '--debug' }

puts "Start converting"
puts "Input file :  #{input_file_path}"
puts "Onput file :  #{output_file_path}"
sleep 1

in_codeblock = false
output = ''

# FIXME: Can not use regex named capture with constant
# START_OF_CODE_BLOCK_REGEXP = /\A```([a-z]+)?:(?<import_file_path>[a-z0-9]+\.[a-z]+)/

File.open(input_file_path).each do |line|
  chomped_line = line.chomp

  if /\A```([a-z]+)?:(?<import_file_path>[^\s]+\.[a-zA-Z]+)/ =~ chomped_line
    in_codeblock = true

    puts :START_CODEBLOCK if debug_mode
    puts line if debug_mode

    output += line
    output += File.read(import_file_path).gsub(/[\n\r\s]+\z/, '') + "\n"
  elsif in_codeblock && '```' == chomped_line
    puts :END_CODEBLOCK if debug_mode
    puts line if debug_mode

    in_codeblock = false
    output += line
  elsif in_codeblock
    puts :DO_NOTHING if debug_mode
  else
    puts :OTHER_LINE if debug_mode
    puts line if debug_mode

    output += line
  end
end

puts output
File.write(output_file_path, output)

## markdown_to_files.rb
#!/usr/bin/env ruby

STDOUT.sync = true

input_file_path = ARGV[0] || (raise 'Please specify file path in command first argument')

debug_mode = !!ARGV.detect { |argv| argv == '--debug' }

puts "Start converting"
puts "Input file :  #{input_file_path}"
sleep 1

in_codeblock = false
file_output = ''
output_file_path_to = nil

File.open(input_file_path).each do |line|
  chomped_line = line.chomp

  if /\A```([a-z]+)?:(?<output_file_path>[^\s]+\.[a-zA-Z]+)/ =~ chomped_line
    output_file_path_to = output_file_path
    in_codeblock = true
    file_output = ''
    puts :START_CODEBLOCK if debug_mode
    puts line if debug_mode
  elsif in_codeblock && '```' == chomped_line
    puts :END_CODEBLOCK if debug_mode
    puts line if debug_mode
    puts output_file_path_to
    File.write(output_file_path_to, file_output)
    in_codeblock = false
  elsif in_codeblock
    puts :FILE_OUTPUT if debug_mode
    puts file_output if debug_mode
    file_output += line
  else
    puts :OTHER_LINE if debug_mode
    puts line if debug_mode
  end
end

## run.sh
#!/bin/bash -eu

chmod +x *.sh
rm -f *.log

for file in $(find . -name '*.sh' | grep -v 'run.sh' | grep -v 'docker.sh'); do
  echo --------------------------
  echo run "$file"
  echo --------------------------
  "$file" 2>&1 | tee "$file".log
done

## subcommand.md
#!/bin/bash -eu

# It is just string assignment
# So subcommand is not executed in this line's timing
```
echo_random_command_as_string='echo $((RANDOM))'
```
# When not use eval, just echo string
```
$echo_random_command_as_string # $((RANDOM))
```
# Eval : execute command from string
# These lines execute `echo $((RANDOM))` everytime
eval $echo_random_command_as_string  # e.g 76811 : randomized every time
eval $echo_random_command_as_string  # e.g 345   : randomized every time
```
eval $echo_random_command_as_string  # e.g 6532  : randomized every time
```
# This is a wrong case ( not exepected result )
# Subcommand is executed immediately when assignment
# So variable got fixed string like 'echo 3457'
```
echo_random_fixed="echo $((RANDOM))"
```
$echo_random_fixed # e.g 3457 : not randomized every time
$echo_random_fixed # e.g 3457 : not randomized every time
```
$echo_random_fixed # e.g 3457 : not randomized every time
```

## subcommand.sh
#!/bin/bash -eu

# It is just string assignment
# So subcommand is not executed in this line's timing
echo_random_command_as_string='echo $((RANDOM))'

# When not use eval, just echo string
$echo_random_command_as_string # $((RANDOM))

# Eval : execute command from string
# These lines execute `echo $((RANDOM))` everytime
eval $echo_random_command_as_string  # e.g 76811 : randomized every time
eval $echo_random_command_as_string  # e.g 345   : randomized every time
eval $echo_random_command_as_string  # e.g 6532  : randomized every time

# This is a wrong case ( not exepected result )
# Subcommand is executed immediately when assignment
# So variable got fixed string like 'echo 3457'
echo_random_fixed="echo $((RANDOM))"

$echo_random_fixed # e.g 3457 : not randomized every time
$echo_random_fixed # e.g 3457 : not randomized every time
$echo_random_fixed # e.g 3457 : not randomized every time

## subcommand.sh.log
+ echo_random='echo $((RANDOM))'
+ echo '$((RANDOM))'
$((RANDOM))
+ echo_random='echo 32537'
+ echo 32537
32537
+ echo 32537
32537
+ echo 32537
32537
+ echo_random='echo $((RANDOM))'
+ eval echo '$((RANDOM))'
++ echo 13431
13431
+ eval echo '$((RANDOM))'
++ echo 8353
8353
+ eval echo '$((RANDOM))'
++ echo 4252
4252

## unexpected.sh
#!/bin/bash -eux

# Assignment as string
command='$((RANDOM))'

# RANDOM command not executed
# Because it only echo string
echo "$command" # $((RANDOM))

# Assignment with executed command result
command="$((RANDOM))"

# RANDOM command not executed
# Because "$command" variable has just string result ( previous set )
echo "$command" # 31424
echo "$command" # 31424
echo "$command" # 31424


# Assignment with executed command result
command="$((RANDOM))"

eval "$command" # bash: 22019: command not found
eval "$command" # bash: 22019: command not found
eval "$command" # bash: 22019: command not found


# Assignment as string
command='$((RANDOM))'

# Error occurs
# below lines evaluate commands as $((RANDOM)) 3 times
eval "$command" # bash: 22019: command not found
eval "$command" # bash: 375: command not found
eval "$command" # bash: 7007: command not found


## unexpected.sh.log
+ command='$((RANDOM))'
+ echo '$((RANDOM))'
$((RANDOM))
+ command=678
+ echo 678
678
+ echo 678
678
+ echo 678
678
+ command=14781
+ eval 14781
++ 14781
./unexpected.sh: line 23: 14781: command not found
	#!/bin/bash -eu

	echo_alice_and_bob='echo alice; echo bob'

	$echo_alice_and_bob # alice; echo bob
	eval $echo_alice_and_bob # alice # bob


	echo_carol_and_david='echo carol && echo david'

	$echo_carol_and_david # bob && echo carol
	eval $echo_carol_and_david # bob # carol

	$echo_alice_and_bob $echo_carol_and_david # alice; echo bob echo carol && echo david
	eval $echo_alice_and_bob $echo_carol_and_david # alice # bob echo carol
	+ echo_alice_and_bob='echo alice; echo bob'
	+ echo 'alice;' echo bob
	alice; echo bob
	+ eval echo 'alice;' echo bob
	++ echo alice
	alice
	++ echo bob
	bob
	+ echo_carol_and_david='echo carol && echo david'
	+ echo carol '&&' echo david
	carol && echo david
	+ eval echo carol '&&' echo david
	++ echo carol
	carol
	++ echo david
	david
	+ echo 'alice;' echo bob echo carol '&&' echo david
	alice; echo bob echo carol && echo david
	+ eval echo 'alice;' echo bob echo carol '&&' echo david
	++ echo alice
	alice
	++ echo bob echo carol
	bob echo carol
	++ echo david
	david
	#!/bin/bash

	# comment
	# commnnt

	code
	code

	# comment

	code
	code # codecomment
	code
	#!/bin/bash

	docker build . -t shell_eval
	docker run shell_eval ./run.sh
	#!/bin/bash -eux

	# Assignment as just string
	command='$((RANDOM))'

	# It works
	# It is equivalent to execute command `echo $((RANDOM))` every times
	eval echo "$command" # e.g. 34641
	eval echo $command # e.g. 755
	eval "echo $command" # e.g. 1235

	# Assignment as just string
	command='$((RANDOM))'

	# It works
	# It is equivalent to execute command `echo $((RANDOM))` every times
	eval echo "$command" # e.g. 27571
	eval echo $command # e.g. 2435
	eval "echo $command" # e.g. 2435
	+ command='$((RANDOM))'
	+ eval echo '$((RANDOM))'
	++ echo 30720
	30720
	+ eval echo '$((RANDOM))'
	++ echo 10733
	10733
	+ eval 'echo $((RANDOM))'
	++ echo 7850
	7850
	+ command='$((RANDOM))'
	+ eval echo '$((RANDOM))'
	++ echo 22658
	22658
	+ eval echo '$((RANDOM))'
	++ echo 24486
	24486
	+ eval 'echo $((RANDOM))'
	++ echo 32756
	32756
	#!/usr/bin/env ruby

	STDOUT.sync = true

	input_file_path = ARGV[0] \|\| (raise 'Please specify file path in command first argument')
	output_file_path = ARGV[1] \|\| input_file_path

	debug_mode = !!ARGV.detect { \|argv\| argv == '--debug' }

	puts "Start converting"
	puts "Input file : #{input_file_path}"
	puts "Onput file : #{output_file_path}"
	sleep 1

	in_codeblock = false
	output = ''

	# FIXME: Can not use regex named capture with constant
	# START_OF_CODE_BLOCK_REGEXP = /\A```([a-z]+)?:(?<import_file_path>[a-z0-9]+\.[a-z]+)/

	File.open(input_file_path).each do \|line\|
	chomped_line = line.chomp

	if /\A```([a-z]+)?:(?<import_file_path>[^\s]+\.[a-zA-Z]+)/ =~ chomped_line
	in_codeblock = true

	puts :START_CODEBLOCK if debug_mode
	puts line if debug_mode

	output += line
	output += File.read(import_file_path).gsub(/[\n\r\s]+\z/, '') + "\n"
	elsif in_codeblock && '```' == chomped_line
	puts :END_CODEBLOCK if debug_mode
	puts line if debug_mode

	in_codeblock = false
	output += line
	elsif in_codeblock
	puts :DO_NOTHING if debug_mode
	else
	puts :OTHER_LINE if debug_mode
	puts line if debug_mode

	output += line
	end
	end

	puts output
	File.write(output_file_path, output)
	#!/bin/bash -eu

	chmod +x *.sh
	rm -f *.log

	for file in $(find . -name '*.sh' \| grep -v 'run.sh' \| grep -v 'docker.sh'); do
	echo --------------------------
	echo run "$file"
	echo --------------------------
	"$file" 2>&1 \| tee "$file".log
	done
	#!/bin/bash -eu

	# It is just string assignment
	# So subcommand is not executed in this line's timing
	```
	echo_random_command_as_string='echo $((RANDOM))'
	```
	# When not use eval, just echo string
	```
	$echo_random_command_as_string # $((RANDOM))
	```
	# Eval : execute command from string
	# These lines execute `echo $((RANDOM))` everytime
	eval $echo_random_command_as_string # e.g 76811 : randomized every time
	eval $echo_random_command_as_string # e.g 345 : randomized every time
	```
	eval $echo_random_command_as_string # e.g 6532 : randomized every time
	```
	# This is a wrong case ( not exepected result )
	# Subcommand is executed immediately when assignment
	# So variable got fixed string like 'echo 3457'
	```
	echo_random_fixed="echo $((RANDOM))"
	```
	$echo_random_fixed # e.g 3457 : not randomized every time
	$echo_random_fixed # e.g 3457 : not randomized every time
	```
	$echo_random_fixed # e.g 3457 : not randomized every time
	```
	+ echo_random='echo $((RANDOM))'
	+ echo '$((RANDOM))'
	$((RANDOM))
	+ echo_random='echo 32537'
	+ echo 32537
	32537
	+ echo 32537
	32537
	+ echo 32537
	32537
	+ echo_random='echo $((RANDOM))'
	+ eval echo '$((RANDOM))'
	++ echo 13431
	13431
	+ eval echo '$((RANDOM))'
	++ echo 8353
	8353
	+ eval echo '$((RANDOM))'
	++ echo 4252
	4252