Adding one line to a directory full of text files

On Thu, 08 Jun 2017 20:23:43 -0400, Paul wrote:
https://stackoverflow.com/questions/...e-copy-command
COPY FILE1+FILE2=FILE1

FILE2 would contain the single line of text you want appended.

Thank you for that helpful advice as that's the only suggestion in this
thread that actually worked even partially on Windows.

I'm still working the problem but I have 2 of 3 issues solved.

Linux aside, there are three components to a Windows solution.
1. For loop (to find all the files of the given extension)
FOR: https://ss64.com/nt/for2.html
2. If query (to ascertain whether the desired line already exists)
IF: https://ss64.com/nt/if.html
3. Append action (to append the desired line to the end of the file).
ECHO: https://ss64.com/nt/echo.html
TYPE: https://ss64.com/nt/type.html
COPY: https://ss64.com/nt/copy.html
REDIRECT: https://ss64.com/nt/syntax-redirection.html

These each work inside a script to always append a given line to all files
of a particular extension.
--------
@echo off
for %%i in (*.bat) do (echo add this command %%i)
--------
@echo off
for %%i in (*.bat) do type append_me2.txt %%i
--------
@echo off
for %%i in (*.bat) do copy %%i+append_me3.txt=%%i
--------

So all I need now is to figure out the IF syntax to query if a certain line
already exists anywhere in the text batch file.

Chaya Eve wrote:
On Thu, 08 Jun 2017 20:23:43 -0400, Paul wrote:
https://stackoverflow.com/questions/...e-copy-command
COPY FILE1+FILE2=FILE1

FILE2 would contain the single line of text you want appended.

Thank you for that helpful advice as that's the only suggestion in this
thread that actually worked even partially on Windows.

I'm still working the problem but I have 2 of 3 issues solved.

Linux aside, there are three components to a Windows solution.
1. For loop (to find all the files of the given extension)
FOR: https://ss64.com/nt/for2.html
2. If query (to ascertain whether the desired line already exists)
IF: https://ss64.com/nt/if.html
3. Append action (to append the desired line to the end of the file).
ECHO: https://ss64.com/nt/echo.html
TYPE: https://ss64.com/nt/type.html
COPY: https://ss64.com/nt/copy.html
REDIRECT: https://ss64.com/nt/syntax-redirection.html

These each work inside a script to always append a given line to all files
of a particular extension.
--------
@echo off
for %%i in (*.bat) do (echo add this command %%i)
--------
@echo off
for %%i in (*.bat) do type append_me2.txt %%i
--------
@echo off
for %%i in (*.bat) do copy %%i+append_me3.txt=%%i
--------

So all I need now is to figure out the IF syntax to query if a certain line
already exists anywhere in the text batch file.

The Windows "findstr" utility is similar to Linux "grep".

I think at some point in this thread, findstr might have been mentioned.

Perhaps you can look for a string that way.

*******

In this example:

https://stackoverflow.com/questions/...-find-a-string

you will see lines like this:

findstr /c:"stringToCheck" "c:\MyFolder\fileToCheck.bat" nul 2&1

The second parameter is the thing they're looking for. The third
parameter is the file name. Now, if this was "grep", it would spit
out one line of text, for each line that matches the specification.

The redirection to NUL, which would be NUL , tosses the text away.
Just the ERRORLEVEL, the return code from the call, is all we want,
to decide whether there is at least one instance in the file. In
Windows, NUL means the same thing as /dev/null in Linux would mean.
And 2&1 redirects STDERR to STDOUT, and STDOUT is going to NUL.
So all possible text output from the findstr is going into the dumper.

At least with grep, you could also get it to print out the
line number of each found occurrence. And then you could
apply some logic, to see if the last line of some grep
output, happened to match the last line number of the file.

The thing is, at some point, a batch file "runs out of juice"
for the job. It becomes inappropriate to do it that way, because
the batch just isn't outfitted well for the job. And perl or gawk
or some other text processing tool is more appropriate. Even then
the chore will be difficult, and could require five lines of code :-)

If you added the necessary logic to your existing scripts
(the scripts that generate the files), then you already know
the necessary line isn't in the file, and can forgo doing this check.

Paul

On Mon, 12 Jun 2017 16:34:23 -0400, Paul wrote:

In this example:

https://stackoverflow.com/questions/...-find-a-string

you will see lines like this:

findstr /c:"stringToCheck" "c:\MyFolder\fileToCheck.bat" nul 2&1

Thank you for finding that find-string command!

I will try it out as that's the only flaw so far in the process of adding a
command to a text batch file already filled with commands.

It turns out that having the command multiple times doesn't hurt anything,
but it's not elegant.

"Chaya Eve" wrote

| I will try it out as that's the only flaw so far in the process of adding
a
| command to a text batch file already filled with commands.
|
| It turns out that having the command multiple times doesn't hurt anything,
| but it's not elegant.

I find that to be a common but odd view. In
many cases, several lines of code can be
compressed into a single line. I once saw a single
line of Perl that was claimed to be able to write
a CD. If I remember correctly it was several hundred
characters, written by someone at MIT. Elegant?
No. Just compact. But it also loses readability. If
readability suffers than re-usability suffers. That
Perl line was merely a useless novelty.

And the process that compact code represents is
not necessarily compact in itself. That depends on
what it does. It might take several pages of programming
code to make a button show in a window. That can be
done in a single line with a component. More efficient or
more elegant? No. The component is only a "wrapper".
The same code is now inside the component and
you've added the overhead of an external library!

In other words, the amount of code has no
direct relationship to the efficiency or streamlining
of the functionality, nor to the usability of the code.