Developer(s) | Various open-source and commercial developers |
---|---|
Operating system | Unix, Unix-like, IBM i |
Platform | Cross-platform |
Type | Command |
License | coreutils: GPLv3+ |
dirname
is a standard computer program on Unix and Unix-like operating systems. When dirname
is given a pathname, it will delete any suffix beginning with the last slash ('/'
) character and return the result. dirname
is described in the Single UNIX Specification and is primarily used in shell scripts.
The version of dirname
bundled in GNU coreutils was written by David MacKenzie and Jim Meyering. [1] The command is available as a separate package for Microsoft Windows as part of the UnxUtils collection of native Win32 ports of common GNU Unix-like utilities. [2] The dirname command has also been ported to the IBM i operating system. [3]
The Single UNIX Specification for dirname
is:
dirname string
string
dirname will retrieve the directory-path name from a pathname ignoring any trailing slashes
$ dirname /home/martin/docs/base.wiki /home/martin/docs$ dirname /home/martin/docs/. /home/martin/docs$ dirname /home/martin/docs/ /home/martin$ dirname base.wiki .$ dirname / /
Since dirname
accepts only one operand, its usage within the inner loop of shell scripts can be detrimental to performance. Consider
whileread file;do dirname "$file"done < some-input
The above excerpt would cause a separate process invocation for each line of input. For this reason, shell substitution is typically used instead
echo"${file%/*}";
or if relative pathnames need to be handled as well
if[ -n "${file##*/*}"];thenecho"."elseecho"${file%/*}";fi
Note that these handle trailing slashes differently than dirname.
We might think that paths that end in a trailing slash are a directory. But actually, the trailing slash represents all files within the directory.
/home/martin/docs/.
The correct way to represent a path as a directory is with a trailing slash and a period.[ according to whom? ][ citation needed ]
uniq
is a utility command on Unix, Plan 9, Inferno, and Unix-like operating systems which, when fed a text file or standard input, outputs the text with adjacent identical lines collapsed to one, unique line of text.
The mkdir
command in the Unix, DOS, DR FlexOS, IBM OS/2, Microsoft Windows, and ReactOS operating systems is used to make a new directory. It is also available in the EFI shell and in the PHP scripting language. In DOS, OS/2, Windows and ReactOS, the command is often abbreviated to md
.
In Unix-like and some other operating systems, the pwd
command writes the full pathname of the current working directory to the standard output.
basename is a standard computer program on Unix and Unix-like operating systems. When basename is given a pathname, it will delete any prefix up to the last slash ('/'
) character and return the result. basename is described in the Single UNIX Specification and is primarily used in shell scripts.
The ln
command is a standard Unix command utility used to create a hard link or a symbolic link (symlink) to an existing file or directory. The use of a hard link allows multiple filenames to be associated with the same file since a hard link points to the inode of a given file, the data of which is stored on disk. On the other hand, symbolic links are special files that refer to other files by name.
A path is a string of characters used to uniquely identify a location in a directory structure. It is composed by following the directory tree hierarchy in which components, separated by a delimiting character, represent each directory. The delimiting character is most commonly the slash ("/"), the backslash character ("\"), or colon (":"), though some operating systems may use a different delimiter. Paths are used extensively in computer science to represent the directory/file relationships common in modern operating systems, and are essential in the construction of Uniform Resource Locators (URLs). Resources can be represented by either absolute or relative paths.
In computing, touch
is a command used to update the access date and/or modification date of a computer file or directory. It is included in Unix and Unix-like operating systems, TSC's FLEX, Digital Research/Novell DR DOS, the AROS shell, the Microware OS-9 shell, and ReactOS. The command is also available for FreeDOS and Microsoft Windows.
In computer programming, glob patterns specify sets of filenames with wildcard characters. For example, the Unix Bash shell command mv *.txt textfiles/
moves all files with names ending in .txt
from the current directory to the directory textfiles
. Here, *
is a wildcard standing for "any string of characters" and *.txt
is a glob pattern. The other common wildcard is the question mark (?
), which stands for one character. For example, mv ?.txt shorttextfiles/
will move all files named with a single character followed by .txt
from the current directory to directory shorttextfiles
, while ??.txt
would match all files whose name consists of 2 characters followed by .txt
.
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.
tr is a command in Unix, Plan 9, Inferno, and Unix-like operating systems. It is an abbreviation of translate or transliterate, indicating its operation of replacing or removing specific characters in its input data set.
In computing, cp
is a command in various Unix and Unix-like operating systems for copying files and directories. The command has three principal modes of operation, expressed by the types of arguments presented to the program for copying a file to another file, one or more files to a directory, or for copying entire directories to another directory.
mv is a Unix command that moves one or more files or directories from one place to another. If both filenames are on the same filesystem, this results in a simple file rename; otherwise the file content is copied to the new location and the old file is removed. Using mv requires the user to have write permission for the directories the file will move between. This is because mv changes the content of both directories involved in the move. When using the mv command on files located on the same filesystem, the file's timestamp is not updated.
In Unix-like and some other operating systems, find
is a command-line utility that locates files based on some user-specified criteria and either prints the pathname of each matched object or, if another action is requested, performs that action on each matched object.
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 to interact with and manipulate a computer's operating system.
In computing, tee
is a command in command-line interpreters (shells) using standard streams which reads standard input and writes it to both standard output and one or more files, effectively duplicating its input. It is primarily used in conjunction with pipes and filters. The command is named after the T-splitter used in plumbing.
test is a command-line utility found in Unix, Plan 9, and Unix-like operating systems that evaluates conditional expressions. test was turned into a shell builtin command in 1981 with UNIX System III and at the same time made available under the alternate name [.
In computing, sleep is a command in Unix, Unix-like and other operating systems that suspends program execution for a specified time.
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, 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.
The Wikibook Guide to Unix has a page on the topic of: Commands |