Yesterday a friend of mine give me this code what extracts a line from a file.
I don't know how it really works, and I need to port it to bash.
#echo off
setlocal EnableDelayedExpansion
set list="List_of_pages.txt"
:: Count lines and generate number
for /f "usebackq" %%c in (`find /V /C "" ^< %list%`) do set lines=%%c
set /a chosen = 0
:AA
set /a chosen = %chosen% +1
set /a skiplines= %chosen% -1
if chosen equ lines goto eof
:: gets the line
set skip=
if %skiplines% gtr 0 set skip=skip=%skiplines%
for /f "usebackq %skip% delims=" %%c in (%list%) do set "current=%%c" & goto continue
:continue
echo %current%
Now, what does for /f "usebackq %skip% delims=" %%c in (%list%) do set "current=%%c" & goto continue mean? What i really don't know what is is that %skip%
Any help though of how that line could be in bash?
Please, Note these basics of batch... which will keep you running to easily convert batch scripts to bash.
All the strings enclosed within % Symbols are Variables. (E.g. %Variable%)
Set is a command used to assign a value to a variable. (or to initialize a variable)
For is a Loop command - and, you must know the work of loop.
The Sub Commands of For command (loop) - UseBackQ, Skip, Delims.
UseBackQ: tells the CMD that, inside FOR LOOP parenthesis, there will be string - if that atring is enclosed by "" (double quotes) then it is a filename (not a simple string), and modifies the usage of ` (ticks) too.
Skip: Tells CMD to skip First N Number of lines from a Text file (It will not read those lines)
Delims: tells from where you want to chop a string (line of file) - e.g. Delims=, will seperate lines into pieces from all commas.
My Analysis:
Here, I think - what this code will do is to take a file, and Return one line of that text file as selected by user.
It is reading a file List_of_pages.txt in line 5. And, it should be Set /p Skip= #Line 12. (Don't count empty lines). And, Returning The selected line #line 14.
Hope, I helped! :)
Related
I've been trying to figure out how to replace an entire line in a text file that contains a certain string using a Batch Script. I've found this solution provided by another user on Stack Overflow, which does the job, however, it just stops iterating through the text file at some random point and in turn, the output file is left with a bunch of lines untransferred from the original file. I've looked character by character, and line by line of the script to figure out what each part exactly does, and can not seem to spot what is causing this bug.
The code provided, thanks to Ryan Bemrose on this question
copy nul output.txt
for /f "tokens=1* delims=:" %%a in ('findstr /n "^" file.txt') do call :do_line "%%b"
goto :eof
:do_line
set line=%1
if {%line:String =%}=={%line%} (
echo.%~1 >> output.txt
goto :eof
)
echo string >> output.txt
The lines it is stopping at always either contain < or > or both and lines with | will either cause it to stop, or sometimes it will delete the line and continue.
To do this robustly, Delayed expansion is necessary to prevent "poison" characters such as < > & | etc being interpreted as command tokens.
Note however that delayed expansion should not be enabled until after the variable containing the line value is defined so as to preserve any ! characters that may be present.
The following will robustly handle all Ascii printable characters *1, and preserve empty lines present in the source file:
#Echo off
Set "InFile=%~dp0input.txt"
Set "OutFile=%~dp0output.txt"
Set "Search=String "
Set "Replace="
>"%OutFile%" (
for /F "delims=" %%G in ('%SystemRoot%\System32\findstr.exe /N "^" "%InFile%"') do (
Set "line=%%G"
call :SearchReplace
)
)
Type "%OutFile%" | More
goto :eof
:SearchReplace
Setlocal EnableDelayedExpansion
Set "Line=!Line:*:=!"
If not defined Line (
(Echo()
Endlocal & goto :eof
)
(Echo(!Line:%Search%=%Replace%!)
Endlocal & goto :eof
*1 Note - Due to how substring modification operates, You cannot replace Search strings that:
contain the = Operator
Begin with ~
This question already has answers here:
Make an environment variable survive ENDLOCAL
(8 answers)
Closed 3 years ago.
I'm trying to use a FOR loop to read the lines in a text file, but I also need to keep track of some variables and evaluate them. The easiest way to do that is by enabling DelyaedExpansion. Actually, it seems to be the ONLY way as everything else I've tried in relation to variables fails miserably if I don't use it. Unfortunately, this means that if any of the lines of text in the file contain exclamation points, they will be stripped out.
I thought I had found a solution by reading a line of text and putting it into a variable, THEN enabling DelayedExpansion, doing the variable operations, and finally using ENDLOCAL & SET VARIABLE=%VARIABLE% to preserve the value. Unfortunately that doesn't seem to work if the ENDLOCAL statement is inside a loop.
For example;
echo off
for /F "delims=" %%F in (test.txt) do (
set Line=%%F
setlocal enabledelayedexpansion
set /a Count=Count+1
echo !Count! - !Line!
endlocal & set Count=%Count%
)
echo Total: %Count%
Each time the loop repeats, the value of "Count" is reset to zero.
If I move the SETLOCAL command before the FOR command, it will strip any "!" from the text, which is unacceptable.
Please note: The example above is only a small part of a much larger script that does many things with the variables inside the loop. I have boiled the problem down to the bare minimum to make it easy to understand. I need to preserve "!" in text read from a file while also being able to perform multiple variable operations within each loop.
So I either need a way to read text from a file, one line at a time, with DeleyedExpansion enabled AND preserve any "!" in the text, or preserve the value of variables that are defined within the SETLOCAL/ENDLOCAL commands within a loop.
With Help from dbenham and his answer here, There is a Solution that exists for this Scenario.
The key, as Dave has Shown, is in Setting the variables PRIOR to using SetlocalEnableDelayedExpansion so that ! is preserved.
#echo off
Set "count=0"
For /F "delims=" %%F in (test.txt) do (
Call :LineParse "%%~F"
)
REM The Below Loop demonstrates Preservation of the Values
Setlocal EnableDelayedExpansion
For /L %%a in (1,1,!count!) DO (
ECHO(!line[%%a]!
)
Endlocal
pause
exit
:LineParse
Set /a count+=1
Set "Line[%count%]=%~1"
Setlocal EnableDelayedExpansion
ECHO(!Line[%count%]!
ECHO(Total: !count!
(
ENDLOCAL
)
GOTO :EOF
There are still a few characters that will not be parsed as desired with this Method, noted in test.txt:
test.txt
Safe Characters: ! > * & ` ' . ] [ ~ # # : , ; ~ } { ) ( / \ ? > < = - _ + $ |
problem Characters: ^ "" %%
problem examples:
line disappears " from single doublequote
but not "" from escaped doublequote
%% will not display unless escaped. % unescaped Percent Symbols will attempt to expand %
caret doubles ^ ^^ ^^^
Don't need to complicate...
Just replace:
echo/ to set /p
setlocal enabledelayedexpansion to cmd /v /c
#echo off
for /F "delims=" %%F in ('type test.txt')do set /a "Count+=1+0" && (
(echo/ & cmd /v/s/c "set/p "'=!Count! - %%F"<nul")>>".\newfile.txt")
cmd /v /c echo/ Total: !Count! && call set "Count="<nul && goto :EOF
I have created command script for reading %N% lines from file. The problem is I can't delete " from anywhere in all text streams when I work with file's text. " deletion is very needed because if file's text line have substring like "text" and text have special chars or even worse, script code, then the script crashes or works not proper way (including script control capturing by programmer who specially composed the text).
If I can't delete " from the text stream(s), then I just want to identify, that the file (or it's first %N% lines, including empty lines) contains at least one " char.
Any thoughts are appreciated, including any file preprocessing. But main aim is script speed.
for /f "skip=2 delims=" %%a in ('find /v /n "" "file" 2^>nul') do set "v=%%a"&call :v&if not errorlevel 1 goto FURTHER1
goto FURTHER2
:v
for /f "delims=[]" %%a in ("%v%") do set "line%%a=%v:*]=%"&if %%a lss %N% (exit /b 1) else exit /b 0
#ECHO Off
SETLOCAL
SET "sourcedir=U:\sourcedir"
SET "filename1=%sourcedir%\q39558311.txt"
SET "tempfilename1=%sourcedir%\q39558311#.txt"
>"%tempfilename1%" ECHO("
SET /a linefound=0
FOR /f "tokens=1 delims=:" %%a IN ('findstr /n /g:"%tempfilename1%" "%filename1%"') DO (
IF %%a gtr 2 SET /a linefound=%%a&GOTO report
)
:report
ECHO quote found AT line %linefound%
DEL "%tempfilename1%"
GOTO :EOF
You would need to change the setting of sourcedir and filename1 to suit your circumstances.
tempfile1 can be any name - it's just a temporary file; I chose that particular name for convenience.
I used a file named q39558311.txt containing some dummy data for my testing.
Essentially, create a file containing a single quote on a single line *tempfile1) then use findstr with the /g:filename option to read in the target strings to find. When findstr finds the line, it numbers it and outputs line_number:line found. Using : as a delimiter, token 1 of this line is the line number.
I don't understand why you've used the skip=number in your code. Do you intend to skip testing the first 2 lines of the target file?
the IF %%a gtr 2 tests the line number found. If it is greater than 2, then the variable linefound is set and the for loop is terminated.
I chose to initialise linefound to zero. It will remain zero if no " is found in lines 2..end. Equally, you could clear it and then it will be defined (with a value of first-line-found-with-quote-greater than-2) and no defined on not found.
I can only identify ", but not delete. Waiting for your suggestions on it!
>nul 2>&1 findstr /m \" "file"
if not errorlevel 1 echo double quote found!
I have a file "file.txt" which contains the output of "dir /s /b *.c"
I want to write this whole content of file.txt in a single variable .
Any ideas?
The usual way to treat questions like this one is to reply: "What do you want this for?". However, your question is pure and simple, so here is the answer. The Batch file below not just store the contents of file.txt in a single variable, but it also later process the variable value as individual lines.
EDIT: I added the method to extract individual lines from the variable value as substrings.
#echo off
setlocal EnableDelayedExpansion
rem Create variables with LF and CR values:
set LF=^
%empty line 1/2, don't remove%
%empty line 2/2, don't remove%
for /F %%a in ('copy /Z "%~F0" NUL') do set CR=%%a
rem Store the contents of file.txt in a single variable,
rem end each line with <CR><LF> bytes
set "variable="
for /F "delims=" %%a in (file.txt) do (
set "variable=!variable!%%a!CR!!LF!"
)
rem 1- Show the contents of the variable:
echo !variable!
rem 2- Process the contents of the variable line by line
echo/
set i=0
for /F "delims=" %%a in ("!variable!") do (
set /A i+=1
echo Line !i!- %%a
)
rem Get the starting position and length of each line inside the variable
set /A i=0, lastStart=0
for /F "delims=:" %%a in (
'(cmd /V:ON /C set /P "=^!variable^!" ^& echo/^) ^<NUL ^| findstr /O "^^"'
) do (
set /A len[!i!]=%%a-lastStart-2, i+=1
set /A start[!i!]=%%a, lastStart=%%a
)
set "len[0]="
set "start[%i%]="
set /A lastLine=i-1
rem 3- Extract individual lines from the variable contents as substrings
:getNumber
echo/
set "num="
set /P "num=Enter line number (nothing to end): "
if not defined num goto end
if %num% gtr %lastLine% echo Invalid number & goto getNumber
for /F "tokens=1,2" %%i in ("!start[%num%]! !len[%num%]!") do (
echo Line %num%- !variable:~%%i,%%j!
)
goto getNumber
:end
You must note that Batch variables can only store a maximum of 8K characters.
No. But you can go through the lines one by one.
for /f "delims=" %A in (file.txt) do echo %A
Maybe say what you are trying to achieve. Knowledge of C won't help you in batch because it's contary for historical reasons.
You can use set /p:
set /p foo=<file.txt
See also this question.
Batch-Script is a very limited tool with a primitive support for multi-line variables (with specific hacks that will not work as expected for this sceneario but if you are interested see this).
The only reasonable solution is to move to a capable language, which is every else less Batch-Script.
Using a .bat script, I want to find a line that says # Site 1 and replace the text in the next line with a variable. I found tutorials on StackOverflow for finding and replacing a line, but not finding a line and replacing the next line. Any help?
#echo off
set "the_file=C:\someFile"
set "search_for=somestring"
set "variable=http://site1"
for /f "tokens=1 delims=:" %%# in ('findstr /n /c:"%search_for%" "%the_file%"') do (
set "line=%%#"
goto :break
)
:break
set /a lineBefore=line-1
set /a nextLine=line+1
break>"%temp%\empty"&&fc "%temp%\empty" "%the_file%" /lb %lineBefore% /t |more +4 | findstr /B /E /V "*****" >newFile
echo %variable%>>newFile
more "%the_file%" +%nextLine% 1>>newFile
echo move /y newFile "%the_file%"
Check if newFile is ok and remove the echo at the front of the last line.
you need to set the three variables at the beginning by yourself.Have on mind that more command sets spaces instead of tabs
#ECHO OFF
SETLOCAL
SET "filename=q28567045.txt"
SET "afterme=# Site 1"
SET "putme=put this line after # Site 1"
SET "skip1="
(
FOR /f "usebackqdelims=" %%a IN ("%filename%") DO (
IF DEFINED skip1 (ECHO(%putme%) ELSE (ECHO(%%a)
SET "skip1="
IF /i "%%a"=="%afterme%" SET skip1=y
)
)>newfile.txt
GOTO :EOF
Produces newfile.txt
The flag `skip1 to skip the line is first reset, then the file is read line by line.
If the skip1 flag is set, then the replacement line is echoed in place of the line read; if not, the line read is echoed.
Then the skip1 flag is cleared
If the line read to %%a matches the string assigned to afterme then the flag skip1 is set (to y - but it doesn't matter what the value is)
Note that empty lines and those starting ; will be ignored and not reproduced - this is standard behaviour of for /f.
If you want to replce the starting file, then simply add
move /y newfile.txt "%filename%"
before the goto :eof line.
Even though I enjoy working with batch, I generally avoid using pure native batch to edit text files because a robust solution is usually complicated and slow.
This can be done easily and efficiently using JREPL.BAT - a hybrid JScript/batch utility that performs regular expression replacement. JREPL.BAT is pure script that runs natively on any Windows machine from XP onward.
#echo off
setlocal
set "newVal=Replacement value"
call jrepl "^.*" "%newValue%" /jbeg "skip=true" /jendln "skip=($txt!='# Site 1')" /f test.txt /o -
The /F option specifies the file to process
The /O option with value of - specifies to replace the original file with the result.
The /JBEG option initializes the command to skip (not replace) each line.
The /JENDLN option checks the value of each line just before it is written out, and sets SKIP off (false) if it matches # Site 1. The next line will be replaced only when SKIP is false.
The search string matches an entire line.
The replacement string is your value stored in a variable.
This problem is similar to this one and may use an equivalent solution. The pure Batch file solution below should be the fastest one of its kind.
#echo off
setlocal EnableDelayedExpansion
set "search=# Site 1"
set "nextLine=Text that replaces next line"
rem Get the line number of the search line
for /F "delims=:" %%a in ('findstr /N /C:"%search%" input.txt') do set /A "numLines=%%a-1"
rem Open a code block to read-input-file/create-output-file
< input.txt (
rem Read the first line
set /P "line="
rem Copy numLines-1 lines
for /L %%i in (1,1,%numLines%) do set /P "line=!line!" & echo/
rem Replace the next line
echo %nextLine%
rem Copy the rest of lines
findstr "^"
) > output.txt
rem Replace input file with created output file
move /Y output.txt input.txt > NUL
This method will fail if the input file have empty lines and also have other limitations.
For a further description of this method, see this post.