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Full Discussion: awk function to remove lines that contain contents of another file
Top Forums UNIX for Beginners Questions & Answers awk function to remove lines that contain contents of another file Post 303003688 by aberg on Tuesday 19th of September 2017 07:30:24 AM
Old 09-19-2017
awk function to remove lines that contain contents of another file
Hi,

I'd be grateful for your help with the following. I have a file (file.txt) with 10 columns and about half a million lines, which in simplified form looks like this:

Code:
ID     Col1    Col2  Col3....
a        4         2       8
b        5         6       1
c        8         4       1
d        3         5       9
e        8         5       2

I'd like to remove all the lines where, say, "b" and "d" appear in the first (ID) column. The output that I want is:

Code:
ID     Col1    Col2  Col3....
a        4         2       8
c        8         4       1
e        8         5       2

In reality, there are about 100,000 lines that I want to remove.
I therefore have a reference file (referencefile.txt) that lists all the IDs that I want removed from file.txt. In this example, the reference file would simply contain "b" and "d" on successive lines.

I am using grep at the moment, and while it works, it is proving painfully slow.

Code:
grep -v -f referencefile.txt file.txt

Is there a way of using awk (or anything else for that matter) to speed up the process?

Many thanks.

AB
 

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LEARN ABOUT PHP

zgrep

ZGREP(1)						      General Commands Manual							  ZGREP(1)

NAME

       zgrep - search possibly compressed files for a regular expression

SYNOPSIS

       zgrep [ grep_options ] [ -e ] pattern filename...

DESCRIPTION

       Zgrep  invokes  grep  on  compressed  or  gzipped  files.   These  grep	options  will  cause  zgrep  to  terminate  with  an  error  code:
       (-[drRzZ]|--di*|--exc*|--inc*|--rec*|--nu*).  All other options specified are passed directly to grep.  If no file is specified,  then  the
       standard input is decompressed if necessary and fed to grep.  Otherwise the given files are uncompressed if necessary and fed to grep.

       If the GREP environment variable is set, zgrep uses it as the grep program to be invoked.

EXIT CODE

       2 - An option that is not supported was specified.

AUTHOR

       Charles Levert (charles@comm.polymtl.ca)

SEE ALSO

       grep(1), gzexe(1), gzip(1), zdiff(1), zforce(1), zmore(1), znew(1)

																	  ZGREP(1)
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