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Full Discussion: for loop using {1..$t}
Top Forums Shell Programming and Scripting for loop using {1..$t} Post 302715347 by DeCoTwc on Sunday 14th of October 2012 03:49:21 PM
Old 10-14-2012
Quote:
Originally Posted by Jotne
while read does work fine. Smilie

GNU bash, version 4.2.8(1)-release (i686-pc-linux-gnu)
As I told in my first post for i in {1..10} works.

It should be possible to use variable in for loops too.
You can use variables in for loops, but not inside of a {}. Someone else can probably do a better job of explaining this, but the bottom line is it has to do with the order in which the shell interprets what you're putting into it. As I recall (and to be honest, I usually just learn how things work, not why, so you should probably look this up...) the reason is that expanding the {} is the very first thing the shell does, BEFORE it translates the variable into it's value. So, if you're trying to do:

(
Code:
15:45:24\[root@DeCoBoxOmega)
[~]$ x=5

(15:47:46\[root@DeCoBoxOmega)
[~]$ for i in {1..$x};do echo $i;done


What the shell is actually doing is for i in the literal expression {1..$x} because $x doesn't mean anything yet.
 

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RUNUSER(1)							   User Commands							RUNUSER(1)

NAME
runuser - run a command with substitute user and group ID SYNOPSIS
runuser [options] -u user command [argument...] runuser [options] [-] [ user [argument...] ] DESCRIPTION
runuser allows to run commands with substitute user and group ID. If the option -u not given, fallback to su compatible semantic and shell is executed. The difference between the commands runuser and su is that runuser does not ask for password (because it may be executed by root user only) and it uses a different PAM configuration. The command runuser does not have to be installed with suid permissions. When called without arguments runuser defaults to running an interactive shell as root. For backward compatibility runuser defaults to not change the current directory and to only set the environment variables HOME and SHELL (plus USER and LOGNAME if the target user is not root). This version of runuser uses PAM for session management. OPTIONS
-c command, --command=command Pass command to the shell with the -c option. --session-command=command Same as -c but do not create a new session (discouraged). -f, --fast Pass -f to the shell which may or may not be useful depending on the shell. -g, --group=group specify the primary group, this option is allowed for root user only -G, --supp-group=group specify a supplemental group, this option is allowed for root user only -, -l, --login Starts the shell as login shell with an environment similar to a real login: o clears all environment variables except for TERM o initializes the environment variables HOME, SHELL, USER, LOGNAME, PATH o changes to the target user's home directory o sets argv[0] of the shell to '-' in order to make the shell a login shell -m, -p, --preserve-environment Preserves the whole environment, ie does not set HOME, SHELL, USER nor LOGNAME. The option is ignored if the option --login is specified. -s SHELL, --shell=SHELL Runs the specified shell instead of the default. The shell to run is selected according to the following rules in order: o the shell specified with --shell o The shell specified in the environment variable SHELL if the --preserve-environment option is used. o the shell listed in the passwd entry of the target user o /bin/sh If the target user has a restricted shell (i.e. not listed in /etc/shells) the --shell option and the SHELL environment variables are ignored unless the calling user is root. --help Display help text and exit. --version Display version information and exit. CONFIG FILES
runuser reads the /etc/default/runuser and /etc/login.defs configuration files. The following configuration items are relevant for runuser: ENV_PATH (string) Defines the PATH environment variable for a regular user. The default value is /usr/local/bin:/bin:/usr/bin. ENV_ROOTPATH (string) ENV_SUPATH (string) Defines the PATH environment variable for root. The default value is /usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin. ALWAYS_SET_PATH (boolean) If set to yes and --login and --preserve-environment were not specified runuser initializes PATH. EXIT STATUS
runuser normally returns the exit status of the command it executed. If the command was killed by a signal, runuser returns the number of the signal plus 128. Exit status generated by runuser itself: 1 Generic error before executing the requested command 126 The requested command could not be executed 127 The requested command could was not found FILES
/etc/pam.d/runuser default PAM configuration file /etc/pam.d/runuser-l PAM configuration file if --login is specified /etc/default/runuser runuser specific logindef config file /etc/login.defs global logindef config file SEE ALSO
pam(8), shells(5), login.defs(5), su(1) AUTHOR
Derived from coreutils' su which was based on an implemenation from David MacKenzie and Fedora runuser command from Dan Walsh. AVAILABILITY
The runuser command is part of the util-linux package and is available from Linux Kernel Archive <ftp://ftp.kernel.org/pub/linux/utils /util-linux/>. util-linux August 2012 RUNUSER(1)
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