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Shell Programming and Scripting

How can I identify the last saved log?

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Top Forums Shell Programming and Scripting How can I identify the last saved log?
# 8  
Old 10-13-2008
Quote:
Originally Posted by otheus
Actually, Gee-Money is on the ball. If your script is in a particular directory, you don't need find. Just ls. However, his script is unnecessarily complex:
Code:
ls -1t |sed -n '/name.*\.log$/{p;q}'

would do and be a bit quicker. (Normally, ls prints out in columns UNLESS it's printing out to a pipe. The -1 here just emphasizes that.)

No, ls only prints in columns if the output is going to a terminal. Anywhere else (e.g., pipe or redirection), it prints one file per line.
# 9  
Old 10-13-2008
Quote:
Originally Posted by gugs
Our system produce logs when a script is run which may not be daily, the logs have a format: name_YYMMDD.log - both name and .log are consistent, date changes as per the day the script is run.

Is there a way of finding the last saved log?

Since the shell will sort the files automatically, there is no need for any external command:

Code:
set -- name_*.log
shift $(( $# - 1 ))
lastlog=$1

# 10  
Old 10-13-2008
Another cheap and easy way:

Code:
ls -t | grep log$ | head -n 1

I might even use that in a script...
# 11  
Old 10-14-2008

There's nothing cheap about using three external commands when you don't need any.
# 12  
Old 10-14-2008
Quote:
Originally Posted by cfajohnson

There's nothing cheap about using three external commands when you don't need any.
Considering the extremely lightweight task being performed, even three external commands are, in fact, extremely cheap with system resources. Also, the three commands in question are among those that many users have in their UNIX toolbox quite readily; hence the "easy". There's really no advantage to declining to use external commands.
# 13  
Old 10-14-2008
Quote:
Originally Posted by treesloth
Considering the extremely lightweight task being performed, even three external commands are, in fact, extremely cheap with system resources.

Three external commands are always much more expensive in terms of time and systems resources than none.
Quote:
Also, the three commands in question are among those that many users have in their UNIX toolbox quite readily; hence the "easy". There's really no advantage to declining to use external commands.

External commands use many times more resources and time than shell builtin functions and syntax.

If the tasks are lightweight, that's all the more reason for not using heavy external commands.
# 14  
Old 10-14-2008
Quote:
Originally Posted by cfajohnson

Three external commands are always much more expensive in terms of time and systems resources than none....
Sure, and if the original task were anything even vaguely approaching a heavy task, it would make a difference. The original task was extremely lightweight. Many times virtually nil is, in this case, still very much virtually nil. Yes, there is merit in knowing the internal methods; in this particular case, the difference is utterly irrelevant. My goal is add to the body of methods offered, not to claim that mine is the only one, or even the best for all circumstances.
Last edited by treesloth; 10-14-2008 at 04:52 AM..
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