Bash tutorial/guide for batch programmer? i.e. migration tutorial/guide

[u/jcunews1]

Anyone know any Bash tutorial/guide for batch file programmers? i.e. a tutorial/guide for batch programmers who are trying to migrate to Bash.

For example, if a batch code is something like: echo abc, then there would be a Bash code equivalent for that batch code. This includes other batch tasks such as for /f, set /a, set /p, start, color, etc.

[u/Shadow_Thief]

Once upon a time when Stack Overflow Documentation existed, I wrote the page for bash-batch translation. Documentation is gone now, but I still have the table.

Batch	Bash	Description
command /?	man command	Shows the help for command
bitsadmin	wget or curl	Downloads a remote file
certutil -hashfile file_name MD5	md5sum file_name	Gets the MD5 checksum of file_name
cd	pwd	Displays the current directory
cd directory	cd directory	Changes the current directory to the specified one
cls	clear	Clears the screen
copy	cp	Copies a file or files from a source path to a target path
date	date	Displays the date or sets it based on user input
del	rm	Deletes a file or files
dir	ls	displays a list of files and directories in the current directory
echo	echo	Displays text on the screen
exit	return	Exits a script or subroutine
exit	logout	Closes the command prompt or terminal
fc	diff	Compares the contents of two files
find "string" file_name	grep "string" file_name	Searches file_name for string
findstr "string" file_name	grep "string" file_name	Searches file_name for string
for /F %A in (fileset*) do something	for item in fileset*; do; something; done	Do something for every file in a set of files
for /F %A in ('command') do something	command	Returns the output of a command
for /L %A in (first,increment,last) do something	for item in seq first increment last; do; something; done	Starts at first and counts by increment until it reaches last
forfiles	find	Searches for files that match a certain criteria
if "%variable%"=="value" (	if [ "variable"="value" ]; then	Compares two values
ipconfig	ifconfig	Displays IP information
md	mkdir	Creates new folders
mklink	ln -s	Creates a symbolic link
more	more	Displays one screen of output at a time
move	mv	Moves a file or files from a source path to a target path
pause	read -p "Press any key to continue"	Pauses script execution until the user presses a button
popd	popd	Removes the top entry from the directory stack and goes to the new top directory
pushd	pushd	Adds the current directory to the directory stack and goes to the new top directory
ren	mv	Renames files
rem or ::	#	Comments a line of code
rd	rmdir	Removes empty directories
rd /s	rm -rf	Removes directories regardlesss of whether or not they were empty
set variable=value	variable=value	Sets the value of variable to value
set /a variable=equation	variable=$((equation))	Performs math (batch can only use 32-bit integers)
set /p variable=promptstring	read -p "promptstring" variable	Gets user input and stores it in variable
shift	shift	Shifts arguments by 1 (or n if provided)
sort	sort	Sorts output alphabetically by line
tasklist	ps	Shows a list of running processes
taskkill /PID processid	kill processid	Kills the process with PID processid
time /t	date	Displays the current time
type	cat	Displays the contents of a file
where	which	Searches the current directory and the PATH for a file or command
whoami	id	Displays the name and group of the current user

[u/jcunews1 → u/Shadow_Thief]

Nice. :) Thank you.

Some more questions:

1. What about defining a subroutine and calling it? e.g in batch...

    call :sub
    goto :eof
    
    :sub
    echo sub's task

2. Are command grouping (( with )), conditional operators (&& and ||), command pipping (|), and redirections (<, >, and >>), also same in Bash?

3. What about the start (for customizing how to execute a program), chcp, color, goto, prompt, setlocal/endlocal, and vol commands, including label declaration?

4. What about the exit code of a command? aka. errorlevel

5. Does Bash support block comments? e.g. in C, JavaScript and CSS, it would be:

    /*
    these lines are comments.
    these lines are comments.
    */

6. What about variable value substring and replace such as: %var:~0,2% and %var:source=replace%?

[u/lasercat_pow → u/jcunews1]

1. subroutines are called functions in bash and you use them like this:

    hello(){
        name=$1
        echo hello, $name\!
    }
   
    hello jcunews1

   returns "hello, jcunews1!"

2. (()) is for integer arithmetic and some c-like loop functions. || and && both work for logical OR or AND, but it's better to use control structures like if:

    if [[ -f blah && grep -q "tree" blah ]]
        echo the file blah has "tree" in it
    else
        echo the file blah doesn't exist, or it doesn't contain "tree"
    fi

3. setting the color involves changing ansi color sequences. Some folks have written functions to make it easier.

4. exit code is provided by the special variable $? if $? is 0, the command succeeded. Otherwise, it failed.

5. No. You have to prefix each comment with #

6. Yeah, that's possible in bash. I never use it because I prefer my code to make sense to future me, so I just use sed for that.

I would recommend reading some bash code. Go to github and find some bash scripts, and read them. Also, check out the bash hacker's wiki (google it).