trap

trap

Execute a command when the shell receives a signal. Syntax trap [-lp] [[arg] sigspec ...] Key -p Display signal commands (or trap commands for sigspec) -l Print a list of signal names and their corresponding numbers. arg The command to … Continued
tr

tr

Translate, squeeze, and/or delete characters. Syntax tr [options]... SET1 [SET2] `tr’ copies standard input to standard output, performing one of the following operations: * translate, and optionally squeeze repeated characters in the result, * squeeze repeated characters, * delete characters, … Continued
true

true

Do nothing, returning a zero (true) exit status Syntax: true `true’ does nothing except return an exit status of 0, meaning “success”. It can be used as a place holder in shell scripts where a successful command is needed, although … Continued
tsort

tsort

Topological sort, perform a topological sort on the given FILE, or standard input if no input file is given or for a FILE of `-‘. Syntax tsort [options] [file] Options --help --version `tsort' reads its input as pairs of strings, … Continued
tty

tty

Print file name of terminal on standard input, print the file name of the terminal connected to standard input. It prints `not a tty’ if standard input is not a terminal. Syntax tty [option]... Options -s --silent --quiet Print nothing; … Continued
type

type

Describe a command. For each name, indicate how it would be interpreted if used as a command name. Syntax type [-aftpP] name [name ...] Key -a Print all the places that contain an executable named name. This includes aliases and functions, … Continued
ulimit

ulimit

User limits – limit the use of system-wide resources. Syntax ulimit [-acdfHlmnpsStuv] [limit] Key -S Set a soft limit for the given resource -H Set a hard limit for the given resource -a All current limits are reported. -c The … Continued
umask

umask

User’s file creation mask. umask sets an environment variable which automatically sets file permissions on newly created files. i.e. it will set the shell process’s file creation mask to mode. Syntax umask [-p] [-S] [mode] Key mode File creation mask -S … Continued
unalias

unalias

Create an alias, aliases allow a string to be substituted for a word when it is used as the first word of a simple command. Syntax alias [-p] [name[=value] ...] unalias [-a] [name ... ] Key -p Print the current … Continued
uname

uname

Print system information, print information about the machine and operating system it is run on. If no options are given, ‘uname’ acts as if the ‘-s’ option were given. Syntax uname [options]... Options -a --all Print all of the below … Continued