Jump to column in vi

You can jump to a line in vi with <line number>G

To jump to a column on the current line, use <column number>| (pipe character)

Add line after match using ex

This little script is to append a line to a file after a text match, using ex.

This particular one is for /usr/local/etc/sudoers to add a 5 minute timeout to the root sudo.

#!/bin/bash FILE=$1 cp -p $FILE $FILE.old ex $FILE <<EOT /^User_Alias.*UNIX.*wheel a Defaults:UNIX timestamp_timeout=5 . x! EOT

Simple password generator

This generates shadow file entries with MD5 crypted passwords.

If you don't specify a password to use on the command line, it will generate a random 15 character password for you.

NB: You really shouldn't use it with a password on the command line, as this can be seen by other users with the ps command while it's running. I've just done this to simplify the example. This code is a snippet, intended to be used in a larger script where the password would be read from a file or provided on STDIN.


#!/usr/bin/perl
#
#
#
use warnings;
use strict;

my $len = 15;

my $plaintext = shift;
if ( ! $plaintext ) {

    my @chars;
    for my $char (33 .. 126) {
        push @chars, chr($char);
    }
    for (1..$len) {
        $plaintext .= $chars[int(rand($#chars))];
    }

}

my @schars = ('a'..'z','A'..'Z',0..9,'.','/');
my $salt = '';
for (1..8) {
    $salt .= $schars[int(rand($#schars))];
}
my $crypted_pass = crypt($plaintext,'$1$' . $salt )
    or die($!);

print "$plaintext\n$crypted_pass\n";


There are other tools to do this.

For example, on Debian Linux so far I know of:


$ dpkg -S /usr/bin/openssl
openssl: /usr/bin/openssl
$ dpkg -S /usr/bin/mkpasswd
whois: /usr/bin/mkpasswd
$ dpkg -S /usr/bin/makepasswd
makepasswd: /usr/bin/makepasswd


Usage:


$ openssl passwd -1 -stdin <<EOT
passwd
EOT
$1$nRGcgK4T$uI7mxwMxGUt6NQ.lyu42./
$ mkpasswd -5 -s <<EOT
> passwd
> EOT
$1$0rg1g/e9$rh1lfYHX9qkSVihZ9vBcd/
$ makepasswd --crypt-md5 --clearfrom=-
passwd
passwd $1$IEK./reC$UbqosXZvVn6Hv/2Zej.va/


I wanted to run it on Solaris, and I wanted to run it in a Perl program (because the rest of the program I was writing was in Perl)

The openssl and mkpasswd programs are compiled C binaries, makepasswd is written in Perl, but it uses Crypt::OpenSSL::Random to generate better randomness, and the box I needed to run it on didn't have that library.

I expect the rand() in Perl is quite random enough for my needs here!

Yesterday...

You can get yesterday's date with


$(TZ=GMT+24 date +%y%m%d)


(or tomorrow's with -24)

Perl keyword 'our' doesn't work on old Perl

If you need to declare a variable in old (pre 5.6?) Perl, and can't use the 'my' keyword...


#!/usr/bin/perl -w
#
#
#
use strict;
use Getopt::Std;

our $opt_v;
getopts('v');
sub VERBOSE { $opt_v; }


This will fail:


$ ./try.pl
Use of reserved word "our" is deprecated at ./try.pl line 8.
Global symbol "$opt_v" requires explicit package name at ./try.pl line 8.
Execution of ./try.pl aborted due to compilation errors.


You can use this instead:


#!/usr/bin/perl -w
#
#
#
use strict;
use Getopt::Std;

use vars '$opt_v';
getopts('v');
sub VERBOSE { $opt_v; }


There is a discussion on what the error means at http://www.perlmonks.org/?node_id=23916

Registry entries for TheGun

TheGun is a great replacement for notepad on Windows. It's a bit funny with registering itself to open file types though, but if you add these registry entries (which expect it to be in C:\Program Files\TheGun\THEGUN.EXE) it should work the way you want it.


Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.pl\OpenWithList]
"g"="THEGUN.EXE"

[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.txt\OpenWithList]
"g"="THEGUN.EXE"

[HKEY_CURRENT_USER\Software\Microsoft\Windows\ShellNoRoam\MUICache]
"C:\\Program Files\\TheGun\\THEGUN.EXE"="TheGun"
"C:\\Progra~1\\TheGun\\THEGUN.EXE"="TheGun"

[HKEY_CURRENT_USER\Software\Classes\Applications\THEGUN.EXE\shell\open\command]
@="C:\\Progra~1\\TheGun\\THEGUN.EXE %1"

[HKEY_CURRENT_USER_Classes\Applications\THEGUN.EXE\shell\open\command]
@="C:\\Progra~1\\TheGun\\THEGUN.EXE %1"


rpm queries

The rpm options you usually need:

rpm -qa (list all packages installed
rpm -qf /path/to/file (which package provides this file)
rpm -ql (list the files in a package)

http://www.rpm.org/max-rpm/s1-rpm-query-parts.html

NIS & Automount


# vi /var/yp/etc/auto_home
# cd /var/yp
# make auto.home


To flush the old mapping on the client server:


# automount -v


Spark Timezone

To correct the timezone in Spark, create a Spark.vmoptions file (not spark.vmoptions and not Spark.vmoptions.txt) beside the Spark.exe and add this to it:

-Duser.timezone=Europe/London

then restart Spark.

Thanks to:

• http://community.igniterealtime.org/docs/DOC-1151
• http://community.igniterealtime.org/thread/42980

Comand line wrapping

If you're having trouble on Solaris with your command line wrapping at 80 characters so it starts printing again at the start of the line...
Have you logged in via a jump server and have your terminal settings configured in the first machine, which is controlling what the second machine can send back?