using ls to find three unix file times
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mtime - modification time (content change) ls -l
ctime - inode chane time (not content change) ls -cl
atime - access time (not ls but vi file) ls -ul


mehta@mama:~$ ls -l sumdata.txt; ls -lu sumdata.txt; ls -lc sumdata.txt
-rw-r--r-- 1 mehta users 10 2004-07-10 09:48 sumdata.txt
-rw-r--r-- 1 mehta users 10 2005-06-30 23:37 sumdata.txt
-rw-r--r-- 1 mehta users 10 2007-04-18 08:11 sumdata.txt

mehta@mama:~$ cat sumdata.txt

mehta@mama:~$ ls -l sumdata.txt; ls -lu sumdata.txt; ls -lc sumdata.txt
-rw-r--r-- 1 mehta users 10 2004-07-10 09:48 sumdata.txt
-rw-r--r-- 1 mehta users 10 2007-11-11 10:04 sumdata.txt
-rw-r--r-- 1 mehta users 10 2007-04-18 08:11 sumdata.txt

mehta@mama:~$ chmod 700 sumdata.txt

mehta@mama:~$ ls -l sumdata.txt; ls -lu sumdata.txt; ls -lc sumdata.txt
-rwx------ 1 mehta users 10 2004-07-10 09:48 sumdata.txt*
-rwx------ 1 mehta users 10 2007-11-11 10:04 sumdata.txt*
-rwx------ 1 mehta users 10 2007-11-11 10:06 sumdata.txt*