Posts tagged as linux
John Macfarlane released a new version of Pandoc that has a lot of new enhancements. A lot of things have changed in the Markdown input types and it’s now compatible with PHP Markdown. This is very nice, because a lot of implementations use the extensions defined by PHP Markdown.
I downloaded the dmg file to install it on my MacBook Pro and it works like a charm.
So, I decided to install it on my new CentOS 6 server to build documents there. Well, I was in for a nice surprise.
After cloning the source from github I started as documented in the INSTALL file
make prep
and now I get
Resolving dependencies...
cabal: cannot configure directory-1.1.0.0. It requires old-time ==1.0.*
For the dependency on old-time ==1.0.* there are these packages:
old-time-1.0.0.0, old-time-1.0.0.2, old-time-1.0.0.3, old-time-1.0.0.4,
old-time-1.0.0.5, old-time-1.0.0.6 and old-time-1.0.0.7.
However none of them are available.
old-time-1.0.0.0 was excluded because pandoc-1.10.0.5 requires old-time ==1.1.*
old-time-1.0.0.7 was excluded because pandoc-1.10.0.5 requires old-time ==1.1.*
etc.
I kept tweaking the makefile and tried almost everything possible, but I was caught in a cyclic dependency loop. So, time to rethink and use Google.
I had already figured out it had to do with a cabal and ghc version that are to old, so it’s time to update.
I found newer Cabal versions at JustHub.
I started removing every RPM with haskel or ghc in the name and removed ~/.cabal and ~/.ghc directories to start of fresh. Then:
sudo rpm -Uhv
http://sherkin.justhub.org/el6/RPMS/x86_64/justhub-release-2.0-4.0.el6.x86_64.rpm
export PATH=/usr/hs/bin:~/.cabal/bin:$PATH
cabal install cabal-dev
cd ~/pandoc
make prep
.
.
Now it compiles but it breaks with:
make install
cabal-0.14.0: Error: some packages failed to install:
pandoc-1.10.0.5 failed during the tests phase. The exception was:
ExitFailure 1
cabal --config-file=/home/tonk/qq/pandoc/cabal-dev/cabal.config:
/usr/hs/tools/cabal-0.14.0 failure (return code=1)
make: *** [install] Error 1
Some tests fail, but I just removed --enable-tests from the Makefile and I got a working executable. Simply copy it to the ~/.cabal/bin directory, install the man-page and everything is fine.
I think it should be simpler, but for now I’m a happy camper.
Today a colleague asked me to sync some files to a server
that is not listening on SSH port 22.
I normally create a configuration entry in my ~/.ssh/config file,
like
Host tosync
Hostname syncer.example.com
Port 1234
User syncuser
and then command
rsync -va --progress --inplace . tosync:
But this time I didn't want to create the entry in my SSH configuration,
because I need this trick in a script. So I started to read the rsync
manpage and after some experimenting I found
rsync -va --progress --inplace --rsh='ssh -p1234' . syncuser@syncer.example.com:
This syncs the current directory to host syncer.example.com on port
1234 as user syncuser.
After upgrading my MySQL database server from version 5.0.95 to 5.1.61 I
suddenly got these errors in the backup logging.
mysqldump: Couldn't execute 'SELECT /*!40001 SQL_NO_CACHE */ * FROM `EVENTS`': Cannot
proceed because system tables used by Event Scheduler were found damaged at server start
(1577)
dbdump gave errorcode 2 for database 'information_schema'
2012-08-09 09:07:53 -> Finished MySQL backup on host 'xxx.tonkersten.com'
Hmm, no idea what has happened. I hope I didn't do something stupid.
Asking Google I found out that the information_schema tables where
changed during the upgrade and that I could recreate the error with:
mysql> use information_schema
Database changed
mysql> SELECT /*!40001 SQL_NO_CACHE */ * FROM EVENTS;
ERROR 1577 (HY000): Cannot proceed because system tables used by Event Scheduler were found damaged at server start
mysql> Bye
So I tried to repair the error with:
mysql_upgrade -u root -h localhost -p --verbose
but still the same error.
Turns out that the MySQL server needs to be restarted for this to work.
Now I get
mysql> use information_schema
Database changed
mysql> SELECT /*!40001 SQL_NO_CACHE */ * FROM EVENTS;
Empty set (0.00 sec)
mysql> Bye
Today the classic, and old, Common Desktop Environment (a.k.a. CDE) was
released into the Open Source world.
You can get the very alpha version at
SourceForge.
I haven't been able to get a running version by now, but I keep
trying.
Good job, guys.
Working with git a lot I decided I needed some git status
in my prompt.
I searched the web and some solutions where almost what I wanted
and this one by Sebastian Celis
came very close.
But it didn't work with my version of zsh, because that didn't seem
to understand the =~ operator.
I also think Sebastian makes things over complicated and so I changed
some things aroud.
This is what I came up with:
First make sure this code is included in your ~/.zshenv file
prompt_git_info()
{
unset __GIT_BRANCH
unset __GIT_BRANCH_STATUS
unset __GIT_BRANCH_DIRTY
local st="$(git status 2>/dev/null)"
if [[ -n "$st" ]]; then
local -a arr
arr=(${(f)st})
if [[ $arr[1] = *Not\ currently\ on\ any\ branch.* ]]
then
__GIT_BRANCH='no-branch'
else
__GIT_BRANCH="${arr[1][(w)4]}"
fi
if [[ $arr[2] = *Your\ branch\ is* ]]
then
if [[ $arr[2] = *ahead* ]]
then
__GIT_BRANCH_STATUS='ahead'
elif [[ $arr[2] = *diverged* ]]
then
__GIT_BRANCH_STATUS='diverged'
else
__GIT_BRANCH_STATUS='behind'
fi
fi
if [[ $st = *nothing\ to\ commit* ]]
then
__GIT_BRANCH_DIRTY='0'
else
__GIT_BRANCH_DIRTY='1'
fi
fi
if [[ -n "$__GIT_BRANCH" ]]
then
local s="("
s+="$__GIT_BRANCH"
case "$__GIT_BRANCH_STATUS"
in
ahead) s+="↑" ;;
diverged) s+="↕" ;;
behind) s+="↓" ;;
esac
if [[ "$__GIT_BRANCH_DIRTY" = "1" ]]
then
s+="⚡"
fi
s+=")"
printf " %s%s" "%{${fg[yellow]}%}" $s
fi
}
and set your prompt to something like this
PS1=$'$C_CYAN%n@%m$(prompt_git_info) $C_WHITE%2~$ $C_OFF'
When I now switch to a directory that is under control of git I get gt status
messages in my prompt, like
tonk@mach (master⚡) ~/dir$ git commit -a
[master fca5ac3] Nice, new stuff.
6 files changed, 88 insertions(+), 12 deletions(-)
tonk@mach (master↑) ~/.dir$ git status
# On branch master
# Your branch is ahead of 'origin/master' by 1 commit.
#
nothing to commit (working directory clean)
tonk@mach (master↑) ~/.dir$
When installing a minimal CentOS 6 system, minimal really, really means
minimal. After a reboot the network interfaces do not start, so network
connectivity is non existing.
Looking into that I noticed that the file
/etc/sysconfig/network-scripts/ifcfg-eth0 contained
DEVICE=eth0
HWADDR=11:22:33:44:55:66
NM_CONTROLLED=yes
ONBOOT=no
BOOTPROTO=dhcp
TYPE=Ethernet
USERCTL=no
PEERDNS=yes
IPV6INIT=no
The lines that mess things up are NM_CONTROLLED=yes meaning the interfaces
are managed with NetworkManager, which isn’t actually installed as part of a
minimal install. You want a minimal install, you get a minimal install. And
ONBOOT=no, meaning "do not start the interface on boot". How stupid is
that!
The trick is to run something like system-config-network-tui to set the IP
addresses manually, but as you might imagine, that's not installed either.
So you best edit /etc/sysconfig/network-scripts/ifcfg-eth0 by hand and set it
to:
DEVICE=eth0
HWADDR=11:22:33:44:55:66
NM_CONTROLLED=no
ONBOOT=yes
BOOTPROTO=none
TYPE=Ethernet
USERCTL=no
PEERDNS=yes
IPV6INIT=no
IPADDR=192.168.0.1
NETMASK=255.255.255.0
GATEWAY=192.168.0.254
DNS1=192.168.0.254
The USERCTL=... line is optional: If set to yes it lets non-root users
control the interface.
After setting this a service network restart will do the trick.
It often happens that I get into a situation
where I need to know key codes of pressed
keys. On my Mac that's simple. Just use the
Key Codes by Many Tricks.
But on Linux I constantly was trying to find
out which key produced what.
So I ended up writing a program for that. I started
of in the shell, but that ended up being rather
tricky and unnecessary complicated. So I redid the
whole thing in C.
This is the result
/*
* Program : code.c
* Author : Ton Kersten
*/
#include <stdio.h>
#include <curses.h>
#define DONE 'q'
#define ESC 0x1b
#define SPC 0x20
char ch;
main()
{
printf("Press '%c' to quit!\n\n", DONE);
/*
* Put the terminal in raw mode, with no echo
*/
system("stty raw -echo");
/*
* Print the header
*/
printf("%4s\t%4s\t%4s\t%4s\r\n", "Char", " Hex", " Oct", " Dec");
printf("%4s\t%4s\t%4s\t%4s\r\n", "----", "----", "----", "----");
/*
* Set the initial loop value to something odd
*/
ch = DONE-1;
while ( ch != DONE )
{ ch = getchar();
/*
* Character read. Display it. Look out for < 0x20
*/
if ( ch < SPC )
{ if ( ch == ESC )
{ /*
* Esc. Just say 'Esc'
*/
printf("%-4s\t0x%02x\t%04o\t%04d\r\n",
"Esc", ch, ch, ch);
}
else
{ /*
* < ' '. Print Control character
*/
printf("^%-c\t0x%02x\t%04o\t%04d\r\n",
ch-1+'A', ch, ch, ch);
}
}
else
{ /*
* Normal character. Display it normally
*/
printf("%-4c\t0x%02x\t%04o\t%04d\r\n",
ch, ch, ch, ch);
}
}
/*
* Put the terminal back to something usefull
*/
system("stty sane echo");
}
And this is an example of the output
Press 'q' to quit!
Char Hex Oct Dec
---- ---- ---- ----
Esc 0x1b 0033 0027
O 0x4f 0117 0079
P 0x50 0120 0080
Esc 0x1b 0033 0027
[ 0x5b 0133 0091
2 0x32 0062 0050
4 0x34 0064 0052
~ 0x7e 0176 0126
q 0x71 0161 0113
During one of my teaching sessions a student
asked me if it was possible to find the number
of spaces in a variable.
As with all questions in Linux and UNIX the answer is
a simple
Of course that's possible. In UNIX and Linux everything
is possible.
With some sed or awk this can be done within
seconds. But I wanted it done completely within
the shell, in this case bash.
This is what I came up with
P="John and Paul and Ringo and George where the Beatles"
R=${P//[! ]/} # Remove everything that is NOT a space
echo ${#R} # Show the number of characters (spaces) that are left
And this also works in the Korn shell (ksh) and the Z-shell (zsh).
Today I've posted a new version of the header program.
Nothing really fancy happened, just added support for zonefiles, in this
case the Bind ones.
It's available at the usual places.
I'm creating a Puppet Starter Kit with some standard manifests included and a
complete set of documentation. All documentation should be written in
Markdown and will be served
by Markdoc. But I want to generate all Markdown files
from the Puppet manifests, so I only need to document the manifest file.
Generating the Markdown is not that difficult, except that I kept ending up
with empty lines at the top of the manifest code and I wanted to get rid of
those. Of course this should be done with sed, because the whole generation
process is written in bash. When playing around with sed I found
which, I think, is genius in it's simplicity. After you find something, do not
remove. Life in UNIX and Linux is nice!
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