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Top Forums Shell Programming and Scripting File descriptors, redirecting output, and stdout Post 302675775 by Michael_K on Monday 23rd of July 2012 02:16:00 PM
Old 07-23-2012
Corona688,

Thank you for the advice.

Multiple users in different parts of my organization will end up using this script. I decided to write to 3 and 4 because I did not want other users controlling where the log files got written, such as by calling the script as:
Code:
 
myscript.ksh > /some/other/location/output.log 2>&1

I'm paranoid; I hope that is forgivable. Smilie

... I think I understand what you're saying, though.

Even if someone does try to co-opt my output using the redirect shown above, the script wrangles the output I defined for 2, overriding the other users' redirects.

I tried it and it seems to work that way. Thanks! I never thought about doing it this way.
 

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log(8)							      System Manager's Manual							    log(8)

NAME
log - Records input and output from a program SYNOPSIS
/usr/sbin/log <logfile> <command> OPERANDS
The file in which to record the interaction being logged. The command to execute. DESCRIPTION
The log program runs <command> and logs the input to and output from <command> to the <logfile> file. Input and output are logged until <command> exits, the log program exits, and the exit status of <command> is returned. The log program is used by the system installation procedure and the it(8) command to create the /var/adm/smlogs/install.log and /var/adm/smlogs/it.log installation log files. RESTRICTIONS
Because the log program is used in the installation standalone environment, program size was the greatest concern in its implementation. The log program does not search for the PATH variable to locate <command> and error messages are terse. The log program causes <command> to take standard input from and write standard output and standard error to UNIX pipes. Some commands will not be able to operate in this environment; therefore, it is suggested that you use the script(1) command instead. UNIX shells will not issue prompts when run from log unless the shell is started with an explicit interactive switch (-i for most shells). For example, log foo.tmp /sbin/sh -i In the previous example, foo.tmp is the name of <logfile>. The log program intercepts end-of-file (usually Ctrl/d). Therefore programs which normally receive end-of-file as an exit command must exit by some other means. ERRORS
Log open error Explanation: The log program was unable to open <logfile>. Verify that the directory exists and that ownerships and permissions are set correctly. Exec Error Explanation: The log program was unable to execute <command>. Verify that you specified a full pathname for <command> and that <command> is an exe- cutable file. Fork Error Explanation: The log program was unable to create one of the processes it requires to log data. SEE ALSO
Commands: it(8), script(1) log(8)
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