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Full Discussion: How to read each file grep a value from that?
Top Forums Shell Programming and Scripting How to read each file grep a value from that? Post 303005859 by MadeInGermany on Tuesday 24th of October 2017 07:06:02 AM
Old 10-24-2017
As Don stated already, the -i option makes things slower, and is not required here.
The problem was that the (useless) use of cat the file names disappear:
Code:
cat *.log | egrep 'Calling appalert|Completed'

because egrep sees only one input stream.
Simply let egrep open the files, so it sees the file names and even prefixes them by default.
Code:
egrep 'Calling appalert|Completed' *.log

If you want to ensure it prefixes the file name even if there is only one log file, then do as Don suggested
Code:
egrep -H 'Calling appalert|Completed' *.log

or, if your grep -E or egrep does not support the -H option, use the /dev/null trick
Code:
egrep 'Calling appalert|Completed' /dev/null *.log

The trick is that grep sees one more file /dev/null that is empty (so will never match anything in it).
 

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LEARN ABOUT LINUX

xzegrep

XZGREP(1)							     XZ Utils								 XZGREP(1)

NAME

       xzgrep - search compressed files for a regular expression

SYNOPSIS

       xzgrep [grep_options] [-e] pattern file...
       xzegrep ...
       xzfgrep ...
       lzgrep ...
       lzegrep ...
       lzfgrep ...

DESCRIPTION

       xzgrep  invokes	grep(1)  on  files  which may be either uncompressed or compressed with xz(1), lzma(1), gzip(1), or bzip2(1).  All options
       specified are passed directly to grep(1).

       If no file is specified, then standard input is decompressed if necessary and fed to grep(1).  When reading from  standard  input,  gzip(1)
       and bzip2(1) compressed files are not supported.

       If  xzgrep  is  invoked as xzegrep or xzfgrep then egrep(1) or fgrep(1) is used instead of grep(1).  The same applies to names lzgrep, lze-
       grep, and lzfgrep, which are provided for backward compatibility with LZMA Utils.

ENVIRONMENT

       GREP   If the GREP environment variable is set, xzgrep uses it instead of grep(1), egrep(1), or fgrep(1).

SEE ALSO

       grep(1), xz(1), gzip(1), bzip2(1), zgrep(1)

Tukaani 							    2010-09-27								 XZGREP(1)
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