since - display content of a file since the last time
since [-aefhlmnqvxz] [-d seconds] [-s
file] files
since is a utility designed to monitor log files.
since is similar to tail(2) as it also displays information
appended to a file. However since only displays the data which has
been added since the last time since was run. If since
is run on a particular file for the first time, then the entire file is
displayed.
since /var/log/apache/{access,error}_log > /dev/null
lynx --dump http://localhost/ > /dev/null
since /var/log/apache/{access,error}_log
- -a
- Make updates to the since state files atomic. This option configures
since to use a temporary file and a rename(2) instead of
updating the state file in situ.
- -d seconds
- Specify the number of integer seconds to wait between polling files for
changes. This option is only relevant in conjunction with the -f
option and if the inotify mechanism is not being used.
- -e
- Print the header lines to standard error instead of standard output.
- -f
- Follow the specified files. This option is analogous to tail -f as
the files are also polled for changes until the process is interrupted.
- -h
- Print a terse help message.
- -l
- Relaxed mode. If some data files are inaccessible since will not
fail completely.
- -m
- Disable mmap(2), use read(2) instead to access state and
data files. Note that for certain smaller io operations read(2) may
be used even if this option has not been given.
- -n
- Do not update the .since file which keeps track of file growth.
- -q
- Make the utility operate more quietly.
- -s filename
- Specify the state file explicitly. Using this option will also disable the
use of fallback state files.
- -v
- Increase the verbosity. This option can be given multiple times.
- -x
- Ignore file arguments which have compressed extensions.
- -z
- Discard output. Similar to redirecting the output to /dev/null, but
faster. If used in conjunction with the -f option, only the initial
output will be discarded.
.since
State file recording the length of the previously
displayed files. The location of the file can be set on the command line using
the
-s option. If this option is not given,
since will check the
SINCE environment variable for the location of the state file. If the
SINCE environment variable has not been set
since will use the
HOME environment variable and store the information in the file
$HOME/.since. If the
HOME variable is not set,
since will
use a
getpwuid(3) lookup. If all these fail will use the file
/tmp/since.
since uses the inode of a file as its key, if that inode is
recycled since will get confused. since is not particularly
efficient when storing or looking up the stat(2) information.
Functionality equivalent to since can probably be achieved with a
number of trivial shell scripts.
since may only be used, distributed and modified in
accordance with the terms of the GPL (GNU General Public License)
version 3 or newer as published by the FSF (Free Software
Foundation).