27} How can I remove all the blank lines from a text file?
Assume e.g. the following LFN-type test file: "My test file.txt"
line 1
line 2 &()[]{}^=;!'+,`~
line 3 <>
line 4
line 7 Lines "5" and "6" are blank!
line 8
line 9 &()[]{}^=;!'+,`~
Several options are available. One pure script solution would be
@echo off & setlocal enableextensions
disabledelayedexpansion
for %%f in ("myfileNoBlanks.txt") do if exist %%f del %%f
for /f "delims=" %%r in ('type "My test file.txt"') do echo.%%r>>"myfileNoBlanks.txt"
endlocal & goto :EOF
The contents of myfileNoBlanks.txt will be
line 1
line 2 &()[]{}^=;!'+,`~
line 3 <>
line 4
line 7 Lines "5" and "6" are blank!
line 8
line 9 &()[]{}^=;!'+,`~
EDitor:
@echo off & setlocal enableextensions
set myfile_=My test file.txt
for /f "tokens=* delims=" %%f in ("%myfile_%") do (
set myfile_=%%~sf)
sed "/^$/d" "%myfile_%"
endlocal & goto :EOF
The renaming to a SFN-format is needed when the SED version usually
assumed in this FAQ is used.
Using
the native FINDSTR is equally easy. This regular expression
solution would appear to be the best, natural option. Either from the
command line or from within a script
findstr /v "^$" "My test file.txt"
Incidentally, note the difference with the literal option
findstr /v /c:"^$" "My test file.txt"
which, expectedly, will not solve the problem at hand.
Likewise,
GAWK could be used
@echo off & setlocal enableextensions
<"My test file.txt" gawk '{if(length($0)!=0)printf"%%s\n",$0}'
endlocal & goto :EOF
@echo off & setlocal enableextensions
<"My test file.txt"
unxgawk "{if(length($0)!=0)printf
\"%%s\n
\",$0}
"
endlocal & goto :EOF
or
@echo off & setlocal enableextensions
set myfile_=My test file.txt
for /f "tokens=* delims=" %%f in ("%myfile_%") do (
set myfile_=%%~sf)
gawk 'length()!=0' "%myfile_%"
endlocal & goto :EOF
or (valid both on 32-bit and 64-bit)
@echo off & setlocal enableextensions
unxgawk "{if(length()>0)printf
\"%%s\n
\",$0}
" "My test file.txt"
endlocal & goto :EOF
you wish to also define as an empty line a line
that has
nothing but blanks or tabs on
it, then use
@echo off & setlocal enableextensions
<"My test file.txt" sed "/^[\x09 ]*$/d"
endlocal & goto :EOF
or
@echo off & setlocal enableextensions
<"My test file.txt" gawk 'NF!=0'
endlocal & goto :EOF
@echo off & setlocal enableextensions
<"My test file.txt" unxgawk "NF!=0"
endlocal & goto :EOF
OK,
but what if you wish to remove all the lines that are two
characters or shorter. Or put in another way, you want to get all
the lines that are at least 3 characters long. This is one way how
to do it
@echo off & setlocal enableextensions
<"My test file.txt" gawk '{if(index(2-length(),"-"))printf"%%s\n",$0}'
endlocal & goto :EOF
@echo off & setlocal enableextensions
<"My test file.txt" unxgawk
"{if(index(2-length(),\"-\"))printf\"%%s\n\",$0}"
endlocal & goto :EOF
or in abbreviated format
@echo off & setlocal enableextensions
<"My test file.txt" gawk 'index(2-length(),"-")'
endlocal & goto :EOF
@echo off & setlocal enableextensions
<"My test file.txt" unxgawk "index(2-length(),\"-\")"
endlocal & goto :EOF
Assume a slightly changed "My test file.txt"
line 1
line 2 &()[]{}^=;!'+,`~
line 3 <>
5
06
line 7 Line "4" is blank, "5" and "6" are short!
line 8
line 9 &()[]{}^=;!'+,`~
A pure command-line script solution is possible
@echo off & setlocal enableextensions
echo ^^$>"%temp%\findstr.tmp"
echo ^^.$>>"%temp%\findstr.tmp"
echo ^^..$>>"%temp%\findstr.tmp"
findstr /v /g:"%temp%\findstr.tmp" "My test file.txt"
for %%f in ("%temp%\findstr.tmp") do (
if exist %%f del %%f)
endlocal & goto :EOF
C:\_D\TEST>cmdfaq
line 1
line 2 &()[]{}^=;!'+,`~
line 3 <>
line 7 Line "4" is blank, "5" and "6" are short!
line 8
line 9 &()[]{}^=;!'+,`~
For demonstration, the problem can also be solved with a Visual
Basic Script (VBScript) aided command line script. Use
"Len(str) > 0"
if the original task is being solved instead of the "two
characters or shorter".
@echo off & setlocal enableextensions
::
:: Build a Visual Basic Script
set skip=
set vbs_="%temp%\tmp$$$.vbs"
findstr "'%skip%VBS" "%~f0" > %vbs_%
::
:: Run the script with Microsoft Windows Script Host Version 5.6
cscript //nologo %vbs_% < "My test file.txt"
::
:: Clean up
for %%f in (%vbs_%) do if exist %%f del %%f
endlocal & goto :EOF
'
'.......................................................
'The Visual Basic Script
'
Do While Not WScript.StdIn.AtEndOfStream 'VBS
str = WScript.StdIn.ReadLine 'VBS
If Len(str) >
2 Then WScript.StdOut.WriteLine str 'VBS
Loop 'VBS
Assorted NT/2000/XP/.. CMD.EXE Script Tricks
