Now here's a useful tool: suppose you want to monitor several files at once. Administrators, for example, might want to keep track of several log files, such as /usr/adm/messages, /usr/adm/lpd-errs, UUCP error files, etc.
|xtail||The xtail program comes in useful for keeping an eye on several administrative log files at once. But it also comes in useful for non-administrators. It's sort of a tail -f for several files as once.|
For example, suppose you want to perform several greps through many files, saving the output in different files. You can then monitor the files using xtail. For example:
grep Berkeley ch?? > Berkeley.grep &%
grep BSD ch?? > BSD.grep &%
grep "System V" ch?? > SystemV.grep &%
grep SysV ch?? > SysV.grep &%
xtail Berkeley.grep BSD.grep SystemV.grep SysV.grep
When new text appears in the files called with xtail, it also appears on the screen:
*** SysV.grep *** ch01:using a SysV-based UNIX system, you must *** Berkeley.grep *** ch01:at the University of California at Berkeley, where *** BSD.grep *** ch03:prefer BSD UNIX systems because they are less likely to ch04:who use a BSD-based UNIX systems must run the *** SysV.grep *** ch04:is a SysV derivative sold by Acme Products Inc.
(When text is written to a new file, the filename is printed
If you press your(usually CTRL-c or DEL), xtail will tell you which files have been modified most recently:
[CTRL-c] *** recently changed files *** 1 4-Nov-92 18:21:12 BSD.grep 2 4-Nov-92 18:19:52 Berkeley.grep 3 4-Nov-92 17:42:45 SysV.grep
To exit xtail, you must send the QUIT signal (usually CTRL-\, control-backslash).
If an argument given to xtail is a directory name and not a filename, then xtail monitors all files in that directory. For administrators, this comes in very useful for monitoring thelog files in all the subdirectories of /usr/spool/uucp/.Log: