SINCE(1) User Manuals SINCE(1)NAME
since - display content of a file since the last time
SYNOPSIS
since [-aefhlmnqvxz] [-d seconds] [-s file] files
DESCRIPTION
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.
EXAMPLE
since /var/log/apache/{access,error}_log > /dev/null
lynx --dump http://localhost/ > /dev/null
since /var/log/apache/{access,error}_log
OPTIONS -a Make updates to the since state files atomic. This option configures since to use a temporary file and a rename(2) instead of updat-
ing 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 inter-
rupted.
-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 ini-
tial output will be discarded.
FILES
.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.
BUGS
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.
COPYING
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).
SEE ALSO tail(1), stat(2).
Linux JULY 1998 SINCE(1)
Check Out this Related Man Page
TAIL(1) BSD General Commands Manual TAIL(1)NAME
tail -- display the last part of a file
SYNOPSIS
tail [-F | -f | -r] [-q] [-b number | -c number | -n number] [file ...]
DESCRIPTION
The tail utility displays the contents of file or, by default, its standard input, to the standard output.
The display begins at a byte, line or 512-byte block location in the input. Numbers having a leading plus ('+') sign are relative to the
beginning of the input, for example, ``-c +2'' starts the display at the second byte of the input. Numbers having a leading minus ('-') sign
or no explicit sign are relative to the end of the input, for example, ``-n 2'' displays the last two lines of the input. The default start-
ing location is ``-n 10'', or the last 10 lines of the input.
The options are as follows:
-b number
The location is number 512-byte blocks.
-c number
The location is number bytes.
-f The -f option causes tail to not stop when end of file is reached, but rather to wait for additional data to be appended to the
input. The -f option is ignored if the standard input is a pipe, but not if it is a FIFO.
-F The -F option implies the -f option, but tail will also check to see if the file being followed has been renamed or rotated. The
file is closed and reopened when tail detects that the filename being read from has a new inode number. The -F option is ignored if
reading from standard input rather than a file.
-n number
The location is number lines.
-q Suppresses printing of headers when multiple files are being examined.
-r The -r option causes the input to be displayed in reverse order, by line. Additionally, this option changes the meaning of the -b,
-c and -n options. When the -r option is specified, these options specify the number of bytes, lines or 512-byte blocks to display,
instead of the bytes, lines or blocks from the beginning or end of the input from which to begin the display. The default for the -r
option is to display all of the input.
If more than a single file is specified, each file is preceded by a header consisting of the string ``==> XXX <=='' where XXX is the name of
the file unless -q flag is specified.
EXIT STATUS
The tail utility exits 0 on success, and >0 if an error occurs.
SEE ALSO cat(1), head(1), sed(1)STANDARDS
The tail utility is expected to be a superset of the IEEE Std 1003.2-1992 (``POSIX.2'') specification. In particular, the -F, -b and -r
options are extensions to that standard.
The historic command line syntax of tail is supported by this implementation. The only difference between this implementation and historic
versions of tail, once the command line syntax translation has been done, is that the -b, -c and -n options modify the -r option, i.e., ``-r
-c 4'' displays the last 4 characters of the last line of the input, while the historic tail (using the historic syntax ``-4cr'') would
ignore the -c option and display the last 4 lines of the input.
HISTORY
A tail command appeared in PWB UNIX.
BSD June 29, 2006 BSD