Top Forums Shell Programming and Scripting awk variables in regex expression ? Post 302486115 by vilius on Friday 7th of January 2011 04:02:47 AM
awk variables in regex expression ?

Hello,

Could someone explain why this one returns nothing:
Code:
$ x=/jon/
$ echo jon | awk -v xa=$x '$1~xa {print}'
$

while the following works fine:
Code:
$ x=jon
$ echo jon | awk -v xa=$x '$1==xa {print}'
$ jon

and the following works fine:
Code:
$ echo jon | awk '$1~/jon/ {print}'
$ jon

using bash.

thanks
V

Last edited by vilius; 01-07-2011 at 05:34 AM..
 
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OPENVT(1)							     Linux 1.x								 OPENVT(1)

NAME
openvt - start a program on a new virtual terminal (VT). SYNOPSIS
openvt [-c vtnumber] [OPTIONS] [--] command DESCRIPTION
openvt will find the first available VT, and run on it the given command with the given command options, standard input, output and error are directed to that terminal. The current search path ($PATH) is used to find the requested command. If no command is specified then the environment variable $SHELL is used. OPTIONS -c, --console=VTNUMBER Use the given VT number and not the first available. Note you must have write access to the supplied VT for this to work; -f, --force Force opening a VT without checking whether it is already in use; -e, --exec Directly execute the given command, without forking. This option is meant for use in /etc/inittab. If you want to use this feature in another context, be aware that openvt has to be a session leader in order for -e to work. See setsid(2) or setsid(1) on how to achieve this. -s, --switch Switch to the new VT when starting the command. The VT of the new command will be made the new current VT; -u, --user Figure out the owner of the current VT, and run login as that user. Suitable to be called by init. Shouldn't be used with -c or -l; -l, --login Make the command a login shell. A - is prepended to the name of the command to be executed; -v, --verbose Be a bit more verbose; -w, --wait wait for command to complete. If -w and -s are used together then openvt will switch back to the controlling terminal when the com- mand completes; -V, --version print program version and exit; -h, --help show this text and exit. -- end of options to openvt. NOTE
If openvt is compiled with a getopt_long() and you wish to set options to the command to be run, then you must supply the end of options -- flag before the command. EXAMPLES
openvt can be used to start a shell on the next free VT, by using the command: openvt bash To start the shell as a login shell, use: openvt -l bash To get a long listing you must supply the -- separator: openvt -- ls -l HISTORY
Earlier, openvt was called open. It was written by Jon Tombs <jon@gtex02.us.es or jon@robots.ox.ac.uk>. The -w idea is from "sam". SEE ALSO
chvt(1), doshell(8), login(1) 19 Jul 1996 V1.4 OPENVT(1)

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