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Full Discussion: Help with Linux hardware fault script in Perl
Top Forums Shell Programming and Scripting Help with Linux hardware fault script in Perl Post 302605401 by Corona688 on Wednesday 7th of March 2012 10:50:41 AM
Old 03-07-2012
Don't take this too harshly, but:

Code:
# Parts that are perl
# Parts that are shell

my $errRpt = `ssh $hostname "grep -s -e '$shortDate' -e '$shortDate2' /var/log/messages|egrep -v ssh|egrep -v cron|egrep -v 'su:'|egrep -v warn|egrep -v segfault|egrep -v success|egrep -v syslog|egrep -v passwd|egrep -v usersense|egrep -v -i patrol|egrep -v -m 10 multipath`;

...fully 93% of this is shell code -- literally running in a shell, since perl creates whole, actual shells every time you use a set of backticks. In a large enough program you could be wasting dozens of shell instances.

I, too, used to write perl code like this. Eventually I threw away the perl, since it did nothing but hold together 19 different shells.

Code:
# Line counts of programs of identical function and logic
$ wc -l perl-backup.pl backup.sh
  49 perl-backup.pl
  25 backup.sh

$

Anyway. About your logic, you can also bundle those handfuls of egrep -v's into a single

Code:
egrep -v 'thing1|thing2|thing3|thing4|thing5|...|thing9

I don't think the -m option makes much sense when using -v.

...but grep doesn't have if-then logic. It's not a language. It can't make decisions later about things that happen now.

awk is a language, which can do absolutely all of that:

Code:
nawk -v SD1="$SHORTDATE1" -v SD2="$SHORTDATE2" '
# Ignore things that don't match SD1 and SD2
!((SD1 ~ \$0) || (SD2 ~ \$0)) { next }
# Ignore things that match these strings
/ssh|cronsu:|warn|segfault|success|syslog|passwd|usersense|[Pp][Aa][Tt][Rr][Oo][Ll]/ { next }

/multipathd/ {
        STR=\$0
        # Blank the date fields for easier comparison
        for(N=1; N<=5; N++) \$N=""
        # Skip messages that've happened before
        if(U[\$0]++) next;
        # Put it back
        \$0=STR
}

1' /var/log/messages

All the red backslashes are junk you need to do this in perl, because it will turn awk's $0/$1/etc into its own variables without it. They're not necessary in shell.
 

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LEARN ABOUT DEBIAN

sieveshell

SIEVESHELL(1)						User Contributed Perl Documentation					     SIEVESHELL(1)

NAME

       sieveshell - remotely manipulate sieve scripts

SYNOPSIS

       sieveshell [--user=user] [--authname=authname] [--realm=realm] [--password=password] [--exec=script] [--execfile=file] server[:port]

       sieveshell --help

DESCRIPTION

       sieveshell allows users to manipulate their scripts on a remote server.	It works via MANAGESIEVE, a work in progress.

       The following commands are recognized:

	   list list scripts on server.

	   put <filename> upload script to server.

	   get <name> [<filename>] get script. if no filename display to stdout

	   delete <name> delete script.

	   activate <name> activate script.

	   deactivate deactivate all scripts.

OPTIONS

       -u user, --user=user
	   The authorization name to request; by default, derived from the authentication credentials.

       -a authname, --authname=authname
	   The user to use for authentication (defaults to current user).

       -r realm, --realm=realm
	   The realm to attempt authentication in.

       -p password, --password=password
	   The password to use when authenticating to server. Note that this parameter can be seen in the process list. Use with caution!

       -e script, --exec=script
	   Instead of working interactively, run commands from script, and exit when done.

       -f file, --execfile=file
	   Instead of working interactively, run commands from file file and exit when done.

REFERENCES

       [MANAGESIEVE] Martin, T.; "A Protocol for Remotely Managing Sieve Scripts", draft-ietf-managesieve-03.txt, Mirapoint, Inc.; May 2001, work
       in progress.

AUTHOR

       Tim Martin <tmartin@mirapoint.com>, and the rest of the Cyrus team <cyrus-bugs@andrew.cmu.edu>.

perl v5.14.2							    2014-06-03							     SIEVESHELL(1)
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