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Full Discussion: Removing Lines if value exist in first file
Top Forums Shell Programming and Scripting Removing Lines if value exist in first file Post 302348776 by Scrutinizer on Saturday 29th of August 2009 04:22:03 PM
Old 08-29-2009
Quote:
Originally Posted by Azhrei
No way would I use a shell for that job! The following Perl script is probably a hundred times faster and more efficient!
While I agree that Perl is usually well suited for this type of application, I do not think this generalization is accurate. The shell scripts above are fine but there is room for some significant speed optimizations. If we use ksh (ksh93s+) instead of bash and a method that resembles the one in your Perl script, I think there would not be a real big difference in speed.

filter.ksh93
Code:
#!/usr/bin/ksh
typeset -A EXCLUDED
EXCLUDE_LIST=$(< $1)
INFILE=$2
for excl in $EXCLUDE_LIST; do
  EXCLUDED[$excl]=1
done
IFS=","
while read a b c id d; do
  if [[ ${EXCLUDED[$id]} -ne 1 ]]; then
    echo "${a},${b},${c},${id},${d}"
  fi
done < $INFILE

Code:
./filter.ksh93 excludes infile > outfile

Last edited by Scrutinizer; 08-29-2009 at 05:32 PM..
 

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LEARN ABOUT DEBIAN

chsh

CHSH(1) 							   User Commands							   CHSH(1)

NAME

       chsh - change login shell

SYNOPSIS

       chsh [options] [LOGIN]

DESCRIPTION

       The chsh command changes the user login shell. This determines the name of the user's initial login command. A normal user may only change
       the login shell for her own account; the superuser may change the login shell for any account.

OPTIONS

       The options which apply to the chsh command are:

       -h, --help
	   Display help message and exit.

       -R, --root CHROOT_DIR
	   Apply changes in the CHROOT_DIR directory and use the configuration files from the CHROOT_DIR directory.

       -s, --shell SHELL
	   The name of the user's new login shell. Setting this field to blank causes the system to select the default login shell.

       If the -s option is not selected, chsh operates in an interactive fashion, prompting the user with the current login shell. Enter the new
       value to change the shell, or leave the line blank to use the current one. The current shell is displayed between a pair of [ ] marks.

NOTE

       The only restriction placed on the login shell is that the command name must be listed in /etc/shells, unless the invoker is the superuser,
       and then any value may be added. An account with a restricted login shell may not change her login shell. For this reason, placing /bin/rsh
       in /etc/shells is discouraged since accidentally changing to a restricted shell would prevent the user from ever changing her login shell
       back to its original value.

FILES

       /etc/passwd
	   User account information.

       /etc/shells
	   List of valid login shells.

       /etc/login.defs
	   Shadow password suite configuration.

SEE ALSO

       chfn(1), login.defs(5), passwd(5).

shadow-utils 4.1.5.1						    05/25/2012								   CHSH(1)
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