patch - apply a diff file to an original

Synopsis
patch [options] [originalfile [patchfile]]

but usually just

patch -pnum

Description
patch takes a patch file patchfile containing a difference listing
produced by the diff program and applies those differences to one or
more original files, producing patched versions. Normally the patched
versions are put in place of the originals. Backups can be made; see
the -b or –backup option. The names of the files to be patched are
usually taken from the patch file, but if there’s just one file to be
patched it can specified on the command line as originalfile. (more…)

diff - find differences between two files

Synopsis
diff [options] from-file to-file

Description
In the simplest case, diff compares the contents of the two files
from-file and to-file. A file name of - stands for text read from the
standard input. As a special case, diff - - compares a copy of stan-
dard input to itself. (more…)

ipcalc - perform simple manipulation of IP addresses

Synopsis
ipcalc [OPTION]… [/prefix] [netmask]

Description
ipcalc provides a simple way to calculate IP information for a host.
The various options specify what information ipcalc should display on
standard out. Multiple options may be specified. An IP address to
operate on must always be specified. Most operations also require a
netmask or a CIDR prefix as well. (more…)

gzip, gunzip, zcat - compress or expand files

Synopsis
gzip [ -acdfhlLnNrtvV19 ] [-S suffix] [ name … ]
gunzip [ -acfhlLnNrtvV ] [-S suffix] [ name … ]
zcat [ -fhLV ] [ name … ]

Description
Gzip reduces the size of the named files using Lempel-Ziv coding
(LZ77). Whenever possible, each file is replaced by one with the
extension .gz, while keeping the same ownership modes, access and mod-
ification times. (The default extension is -gz for VMS, z for MSDOS,
OS/2 FAT, Windows NT FAT and Atari.) If no files are specified, or if
a file name is “-”, the standard input is compressed to the standard
output. Gzip will only attempt to compress regular files. In partic-
ular, it will ignore symbolic links. (more…)

tar - The GNU version of the tar archiving utility

Synopsis
tar <operation> [options]

Description
This manual page documents the GNU version of tar, an archiving pro-
gram designed to store and extract files from an archive file known as
a tarfile. A tarfile may be made on a tape drive, however, it is also
common to write a tarfile to a normal file. The first argument to tar
must be one of the options Acdrtux, followed by any optional func-
tions. The final arguments to tar are the names of the files or
directories which should be archived. The use of a directory name
always implies that the subdirectories below should be included in the
archive. (more…)

ps - report a snapshot of the current processes.

Synopsis
ps [options]

Description
ps displays information about a selection of the active processes. If you
want a repetitive update of the selection and the displayed information,
use top(1) instead.

By default, ps selects all processes with the same effective user ID (EUID)
as the curent user and associated with the same terminal as the invoker. It
displays the process ID (PID), the terminal (tty) associated with the process
(TTY), the cumulated CPU time in [dd-]hh:mm:ss format (TIME), and the
executable name (CMD). The use of BSD-style options will add process state
(STAT) to the default display. The use of BSD-style options will also change
the process selection to include processes on other terminals (TTYs) that are
owned by you; alternately, this may be described as setting the selection to
be the set of all processes filtered to exclude processes owned by other
users or not on a terminal. Output is unsorted by default. (more…)