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Old 02-16-2012, 10:23 PM   #1
Jon Blanchard
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Registered: Feb 2012
Location: Franklin, TN
Distribution: Linux, AIX
Posts: 6

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The single period before a command or shell script filename


Consider the following line from a .profile script:
Code:
if [ -r .profile.local.start ] ; then . .profile.local.start ; fi
                                      ^
How is that single period interpreted, referenced by the caret underneath it? If I am going to run the .profile file in a cron job, do I use the following form?
Code:
00 21 * * * /home/hci/.profile; /home/hci/getstats2.sh
...or does the crontab line need to be the following?
Code:
00 21 * * * . /home/hci/.profile; /home/hci/getstats2.sh
Should I enclose all commands in parens?
Code:
00 21 * * * (. /home/hci/.profile; /home/hci/getstats2.sh)
Thanks in advance for your response.
 
Old 02-16-2012, 10:59 PM   #2
chrism01
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Registered: Aug 2004
Location: Sydney
Distribution: Centos 6.5, Centos 5.10
Posts: 16,251

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the
Code:
.<space>filename>
convention is equiv to the 'source' cmd, which embeds the named file content (usually env settings ala .rpofile) into the current shell env, instead of creating a subshell (which is what happens when you call a shell file).
See http://linux.die.net/man/1/bash & search for 'source'
Quote:
. filename [arguments]
source filename [arguments]
Read and execute commands from filename in the current shell environment and return the exit status of the last command executed from filename. If filename does not contain a slash, file names in PATH are used to find the directory containing filename. The file searched for in PATH need not be executable. When bash is not in posix mode, the current directory is searched if no file is found in PATH. If the sourcepath option to the shopt builtin command is turned off, the PATH is not searched. If any arguments are supplied, they become the positional parameters when filename is executed. Otherwise the positional parameters are unchanged. The return status is the status of the last command exited within the script (0 if no commands are executed), and false if filename is not found or cannot be read.
HTH

See also
http://rute.2038bug.com/index.html.gz
http://tldp.org/LDP/Bash-Beginners-G...tml/index.html
http://www.tldp.org/LDP/abs/html/

As far as cron goes, best to just call a simple cmd eg the shell script and then source or .<space> inside the shell script at the top

Last edited by chrism01; 02-16-2012 at 11:00 PM.
 
  


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