sed is a Unix utility that parses and transforms text, using a simple, compact programming language. sed was developed from 1973 to 1974 by Lee E. McMahon of Bell Labs, and is available today for most operating systems. sed was based on the scripting features of the interactive editor ed and the earlier qed. sed was one of the earliest tools to support regular expressions, and remains in use for text processing, most notably with the substitution command. Popular alternative tools for plaintext string manipulation and "stream editing" include AWK and Perl.
A man page is a form of software documentation usually found on a Unix or Unix-like operating system. Topics covered include computer programs, formal standards and conventions, and even abstract concepts. A user may invoke a man page by issuing the man command.
In computing, ls is a command to list computer files in Unix and Unix-like operating systems. ls is specified by POSIX and the Single UNIX Specification. When invoked without any arguments, ls lists the files in the current working directory. The command is also available in the EFI shell. In other environments, such as DOS, OS/2, and Microsoft Windows, similar functionality is provided by the dir command.
The cd command, also known as chdir, is a command-line OS shell command used to change the current working directory in operating systems such as Unix, DOS, OS/2, TRIPOS, AmigaOS, Microsoft Windows, ReactOS, and Linux. It can be used in shell scripts and batch files. The command is also available in the open source MS-DOS emulator DOSBox and in the EFI shell. The command is named chdir in MPE/iX.
The Unix command su, which stands for substitute user is used by a computer user to execute commands with the privileges of another user account. When executed it invokes a shell without changing the current working directory or the user environment.
xargs is a command on Unix and most Unix-like operating systems used to build and execute commands from standard input. It converts input from standard input into arguments to a command.
join is a command in Unix and Unix-like operating systems that merges the lines of two sorted text files based on the presence of a common field. It is similar to the join operator used in relational databases but operating on text files.
In computing, echo is a command that outputs the strings it is being passed as arguments. It is a command typically used in shell scripts and batch files to output status text to the screen or a computer file, or as a source part of a pipeline.
Signals are a limited form of inter-process communication (IPC), typically used in Unix, Unix-like, and other POSIX-compliant operating systems. A signal is an asynchronous notification sent to a process or to a specific thread within the same process in order to notify it of an event that occurred. Signals originated in 1970s Bell Labs Unix and have been more recently specified in the POSIX standard.
In computing, umask is a command that determines the settings of a mask that controls how file permissions are set for newly created files. In one case it also influences how the file permissions are changed explicitly. umask may also refer to a function that sets the mask, or it may refer to the mask itself, which is formally known as the file mode creation mask. The mask is a grouping of bits, each of which restricts how its corresponding permission is set for newly created files. The bits in the mask may be changed by invoking the umask command.
The remote shell (rsh) is a command line computer program that can execute shell commands as another user, and on another computer across a computer network.
In computing, rm is a basic command on Unix and Unix-like operating systems used to remove objects such as computer files, directories and symbolic links from file systems and also special files such as device nodes, pipes and sockets, similar to the del command in MS-DOS, OS/2, and Microsoft Windows. The command is also available in the EFI shell.
A command shell is a command line interface computer program to an operating system.
env is a shell command for Unix and Unix-like operating systems. It is used to either print a list of environment variables or run another utility in an altered environment without having to modify the currently existing environment. Using env, variables may be added or removed, and existing variables may be changed by assigning new values to them.
In computing, a shebang is the character sequence consisting of the characters number sign and exclamation mark at the beginning of a script. It is also called sha-bang, hashbang, pound-bang, or hash-pling.
In computing, exec is a functionality of an operating system that runs an executable file in the context of an already existing process, replacing the previous executable. This act is also referred to as an overlay. It is especially important in Unix-like systems, although other operating systems implement it as well. Since a new process is not created, the original process identifier (PID) does not change, but the machine code, data, heap, and stack of the process are replaced by those of the new program.
A truss is an architectural structure.
In computing, which is a command for various operating systems used to identify the location of executables. The command is available in Unix and Unix-like systems, the AROS shell, for FreeDOS and for Microsoft Windows. The functionality of the which command is similar to some implementations of the type command. POSIX specifies a command named command that also covers this functionality.
In computer operating systems, mkfs is a command used to format a block storage device with a specific file system. The command is part of Unix and Unix-like operating systems. In Unix, a block storage device must be formatted with a file system before it can be mounted and accessed through the operating system's filesystem hierarchy.
A command-line interface or command language interpreter (CLI), also known as command-line user interface, console user interface and character user interface (CUI), is a means of interacting with a computer program where the user issues commands to the program in the form of successive lines of text. A program which handles the interface is called a command language interpreter or shell (computing).
