Core utilities (Português) - ArchWiki

# Core utilities (Português)

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Este artigo trata dos utilitários chamados core ("principais") em um sistema GNU/Linux, como less, ls e grep. O escopo deste artigo inclui, mas não está limitado a, os utilitários incluídos no pacote GNU coreutils. O que se segue são várias dicas e truques e outras informações úteis relacionadas a esses utilitários.

## Comandos básicos

A tabela a seguir lista os comandos básicos do shell, cada usuário Linux deve estar familiarizado. Veja as seções abaixo e "Artigos relacionados" para obter detalhes.

Comando | Descrição | Página de manual | Exemplo
--- | --- | --- | ---
man | Mostra página de manual para um comando | man(7) | man ed
cd | Muda o diretório (comando embutido no shell) | cd(1p) | cd /etc/pacman.d
mkdir | Cria um diretório | mkdir(1) | mkdir ~/novapasta
rmdir | Remove diretório vazio | rmdir(1) | rmdir ~/pastavazia
rm | Remove um arquivo | rm(1) | rm ~/file.txt
rm -r | Remove diretório e seu conteúdo |  | rm -r ~/.cache
ls | Lista arquivos | ls(1) | ls *.mkv
ls -a | Lista arquivos ocultos |  | ls -a /home/archie
ls -al | Lista arquivos ocultos e propriedades de arquivos |  |
mv | Move um arquivo | mv(1) | mv ~/comprimido.zip ~/archive/comprimido2.zip
cp | Copia uma arquivo | cp(1) | cp ~/.bashrc ~/.bashrc.bak
chmod +x | Torna um arquivo executável | chmod(1) | chmod +x ~/.local/bin/meuscript.sh
cat | Mostrar conteúdo de arquivo | cat(1) | cat /etc/hostname
strings | Mostra caracteres imprimíveis em arquivos binários | strings(1) | strings /usr/bin/free
find | Pesquisa por um arquivo | find(1) | find ~ -name meuarquivo
mount | Monta uma partição | mount(8) | mount /dev/sdc1 /media/usb
df -h | Mostra o espaço restante em todas as partições | df(1) |
ps -A | Mostra todos os processos em execução | ps(1) |
killall | Mata todas as instâncias em execução de um processo | killall(1) |
ss -at | Exibe uma lista de sockets TCP abertos | ss(8) |

## cat

cat é um utilitário padrão do Unix que concatena e lista arquivos.

- Porque o cat não é embutido no shell, em muitas ocasiões você pode achar mais conveniente usar um redirecionamento, por exemplo em scripts, ou se você se preocupa muito com desempenho. De fato, `< arquivo` faz o mesmo que `cat arquivo`.

- cat é capaz de trabalhar com várias linhas:

    $ cat << EOF >> caminho/arquivo
    primeira linha
    ...
    última linha
    EOF

Alternativamente, usando `printf`:

    $ printf '%s\n' 'primeira linha' ... 'última linha'

- Se você precisa listar linhas na ordem reversa, há um utilitários chamado tac (cat inverso).

## dd

dd é um utilitário para o Unix e sistemas operacionais similares Unix, cujo principal objetivo é converter e copiar um arquivo.

Similarmente ao cp, por padrão o dd faz cópia bit a bit do arquivo, mas com recursos de controle de fluxo de E/S de baixo nível.

Dica: Por padrão, dd emite nada até a tarefa está finalizada. Para monitorar o progresso da operação, adicione a opção `status=progress` ao comando. Ela não está disponível em versões antigas (antes 8.24) do coreutils.

Para mais informações, veja dd(1) ou da documentação completa.

## grep

grep (de g/re/p, global/regular expression/print, do ed) é um utilitário de pesquisa de texto de linha de comando originalmente escrito para Unix. O comando grep pesquisa arquivos ou entrada padrão para linhas correspondendo a uma expressão regular dada, e imprime essas linhas para a saída padrão do programa.

- Lembre-se que grep trata de arquivos, então um construto como `cat arquivo | grep padrão` pode ser substituído com `grep padrão arquivo`
- Há alternativas ao grep otimizadas para código fonte em VCS, tal como the_silver_searcher e ack.
- Para incluir números de linha de arquivo na saída, use a opção `-n`.

Nota: Alguns comandos enviam suas saídas para stderr(3) e o grep não tem aparente efeito. Neste caso, redirecione stderr para stdout com `comando 2>&1 | grep args` ou (par Bash 4) `comando |& grep args`. Veja também Redirecionamento de E/S (inglês).

Para suporte a cores, veja Color output in console#grep.

## find

find é parte do pacote findutils, que pertence ao grupo de pacotes base.

Provavelmente se esperaria que um comando find levasse como argumento um nome de arquivo e pesquisasse no sistema de arquivos para arquivos que correspondessem a esse nome. Para um programa que faz exatamente isso, veja #locate abaixo.

Em vez disso, find leva um conjunto de diretórios e combina cada arquivo abaixo deles contra um conjunto de expressões. Este design permite alguns "one-liners" muito poderosos que não seriam possíveis usando o design "intuitivo" descrito acima. Veja UsingFind para detalhes de uso.

## iconv

iconv converte uma codificação de caracteres de um codeset para outro.

O seguinte comando vai converter o arquivo `foo` de ISO-8859-15 para UTF-8, salvando-o em `foo.utf`:

    $ iconv -f ISO-8859-15 -t UTF-8 foo > foo.utf

Veja iconv(1) para mais detalhes.

### Converter um arquivo no lugar

Dica: Você pode usar recode em vez do iconv se você não deseja tocar no mtime.

Ao contrário do sed, iconv não fornece uma opção para converter um arquivo no lugar onde se encontra. Porém, `sponge` do pacote moreutils pode ajudar:

    $ iconv -f WINDOWS-1251 -t UTF-8 foobar.txt | sponge foobar.txt

Veja sponge(1) para detalhes.

## ip

ip allows you to show information about network devices, IP addresses, routing tables, and other objects in the Linux IP software stack. By appending various commands, you can also manipulate or configure most of these objects.

Note: The ip utility is provided by the iproute2 package, which is included in the base group.

Object | Purpose | Manual page
--- | --- | ---
ip addr | protocol address management | ip-address(8)
ip addrlabel | protocol address label management | ip-addrlabel(8)
ip l2tp | tunnel Ethernet over IP (L2TPv3) | ip-l2tp(8)
ip link | network device configuration | ip-link(8)
ip maddr | multicast addresses management | ip-maddress(8)
ip monitor | watch for netlink messages | ip-monitor(8)
ip mroute | multicast routing cache management | ip-mroute(8)
ip mrule | rule in multicast routing policy db |
ip neigh | neighbour/ARP tables management | ip-neighbour(8)
ip netns | process network namespace management | ip-netns(8)
ip ntable | neighbour table configuration | ip-ntable(8)
ip route | routing table management | ip-route(8)
ip rule | routing policy database management | ip-rule(8)
ip tcp_metrics | management for TCP Metrics | ip-tcp_metrics(8)
ip tunnel | tunnel configuration | ip-tunnel(8)
ip tuntap | manage TUN/TAP devices |
ip xfrm | manage IPsec policies | ip-xfrm(8)

The `help` command is available for all objects. For example, typing `ip addr help` will show you the command syntax available for the address object. For advanced usage see the iproute2 documentation.

The Network configuration article shows how the ip command is used in practice for various common tasks.

Note: You might be familiar with the ifconfig command, which was used in older versions of Linux for interface configuration. It is now deprecated in Arch Linux; you should use ip instead.

## locate

Install the mlocate package. The package contains an `updatedb.timer` unit, which invokes a database update each day. The timer is enabled right after installation, start it manually if you want to use it before reboot. You can also manually run updatedb as root at any time. By default, paths such as `/media` and `/mnt` are ignored, so locate may not discover files on external devices. See updatedb(8) for details.

The locate command is a common Unix tool for quickly finding files by name. It offers speed improvements over the find tool by searching a pre-constructed database file, rather than the filesystem directly. The downside of this approach is that changes made since the construction of the database file cannot be detected by locate.

Before locate can be used, the database will need to be created. To do this, execute `updatedb` as root.

See also How locate works and rewrite it in one minute.

## less

This article or section needs expansion.

Reason: less is a complex beast, and this section should explain some of the basic less commands (Discuss in Talk:Core utilities (Português)#)
less is a terminal pager program used to view the contents of a text file one screen at a time. Whilst similar to other pagers such as more and pg, less offers a more advanced interface and complete feature-set.

See List of applications#Terminal pagers for alternatives.

### Vim como alternativa de paginador

Vim includes a script to view the content of text files, compressed files, binaries and directories. Add the following line to your shell configuration file to use it as a pager:

    ~/.bashrc

    alias less='/usr/share/vim/vim80/macros/less.sh'

There is also an alternative to the less.sh macro, which may work as the `PAGER` environment variable. Install vimpager and add the following to your shell configuration file:

    ~/.bashrc

    export PAGER='vimpager'
    alias less=$PAGER

Now programs that use the `PAGER` environment variable, like git, will use vim as pager.

## ls

ls lists directory contents.

See `info ls` or the online manual for more information.

### Formato longo

The `-l` option displays some metadata, for example:

    $ ls -l /path/to/directory

    total 128
    drwxr-xr-x 2 archie users  4096 Jul  5 21:03 Desktop
    drwxr-xr-x 6 archie users  4096 Jul  5 17:37 Documents
    drwxr-xr-x 2 archie users  4096 Jul  5 13:45 Downloads
    -rw-rw-r-- 1 archie users  5120 Jun 27 08:28 customers.ods
    -rw-r--r-- 1 archie users  3339 Jun 27 08:28 todo
    -rwxr-xr-x 1 archie users  2048 Jul  6 12:56 myscript.sh

The `total` value represents the total disk allocation for the files in the directory, by default in number of blocks.

Below, each file and subdirectory is represented by a line divided into 7 metadata fields, in the following order:

- type and permissions:
  - the first character is the entry type, see `info ls -n "What information is listed"` for an explanation of all the possible types; for example:
    - `-` denotes a normal file;
    - `d` denotes a directory, i.e. a folder containing other files or folders;
    - `p` denotes a named pipe (aka FIFO);
    - `l` denotes a symbolic link;
  - the remaining characters are the entry's permissions;
- number of hard links for the entity; files will have at least 1, i.e. the showed reference itself; folders will have at least 2: the showed reference, the self-referencing `.` entry, and then a `..` entry in each of its subfolders;
- owner user name;
- group name;
- size;
- last modification timestamp;
- entity name.

### Nomes de arquivos contendo espaços envoltos por aspas

By default, file and directory names that contain spaces are displayed surrounded by single quotes. To change this behavior use the `-N` or `--quoting-style=literal` options. Alternatively, set the `QUOTING_STYLE` environment variable to `literal`. [1]

## lsblk

lsblk(8) will show all available block devices along with their partitioning schemes, for example:

    $ lsblk -f

    NAME   FSTYPE   LABEL       UUID                                 MOUNTPOINT
    sda
    ├─sda1 vfat                 C4DA-2C4D                            /boot
    ├─sda2 swap                 5b1564b2-2e2c-452c-bcfa-d1f572ae99f2 [SWAP]
    └─sda3 ext4                 56adc99b-a61e-46af-aab7-a6d07e504652 /

The beginning of the device name specifies the type of block device. Most modern storage devices (e.g. hard disks, SSDs and USB flash drives) are recognised as SCSI disks (`sd`). The type is followed by a lower-case letter starting from `a` for the first device (`sda`), `b` for the second device (`sdb`), and so on. Existing partitions on each device will be listed with a number starting from `1` for the first partition (`sda1`), `2` for the second (`sda2`), and so on. In the example above, only one device is available (`sda`), and that device has three partitions (`sda1` to `sda3`), each with a different file system.

Other common block device types include for example `mmcblk` for memory cards and `nvme` for NVMe devices. Unknown types can be searched in the kernel documentation[dead link 2017-11-11].

## mkdir

mkdir makes directories.

To create a directory and its whole hierarchy, the `-p` switch is used, otherwise an error is printed. As users are supposed to know what they want, `-p` switch may be used as a default:

    alias mkdir='mkdir -p -v'

The `-v` switch make it verbose.

Changing mode of a just created directory using chmod is not necessary as the `-m` option lets you define the access permissions.

Tip: If you just want a temporary directory, a better alternative may be mktemp: `mktemp -p`.

## mv

mv moves and renames files and directories.

To limit potential damage caused by the command, use an alias:

    alias mv='timeout 8 mv -iv'

This alias suspends mv after eight seconds, asks for confirmation before overwriting any existing files, lists the operations in progress and does not store itself in the shell history file if the shell is configured to ignore space starting commands.

## od

The od (octal dump) command is useful for visualizing data that is not in a human-readable format, like the executable code of a program, or the contents of an unformatted device. See the manual for more information.

## pv

You can use pv (pipe viewer) to monitor the progress of data through a pipeline, for example:

    # dd if=/source/filestream | pv -monitor_options -s size_of_file | dd of=/destination/filestream

In most cases `pv` functions as a drop-in replacement for `cat`.

## rm

rm removes files or directories.

To limit potential damage caused by the command, use an alias:

    alias rm='timeout 3 rm -Iv --one-file-system'

This alias suspends rm after three seconds, asks confirmation to delete three or more files, lists the operations in progress, does not involve more than one file systems and does not store itself in the shell history file if the shell is configured to ignore space starting commands. Substitute `-I` with `-i` if you prefer to confirm even for one file.

Zsh users may want to put `noglob` before `timeout` to avoid implicit expansions.

To remove directories believed to be empty, use rmdir as it fails if there are files inside the target.

## sed

sed is stream editor for filtering and transforming text.

Here is a handy list of sed one-liners examples.

Tip: More powerful alternatives are AWK and the Perl language.

## seq

seq prints a sequence of numbers. Shell built-in alternatives are available, so it is good practice to use them as explained on Wikipedia.

## ss

ss is a utility to investigate network ports and is part of the iproute2 package in the base group. It has a similar functionality to the deprecated netstat utility.

Common usage includes:

Display all TCP Sockets with service names:

    $ ss -at

Display all TCP Sockets with port numbers:

    $ ss -atn

Display all UDP Sockets:

    $ ss -au

For more information see ss(8) or `ss.html` from the iproute2 package.

## tar

As an early Unix archiving format, .tar files—known as "tarballs"—are widely used for packaging in Unix-like operating systems. Both pacman and AUR packages are compressed tarballs, and Arch uses GNU's tar program by default.

For .tar archives, tar by default will extract the file according to its extension:

    $ tar xvf file.EXTENSION

Forcing a given format:

File Type | Extraction Command
--- | ---
`file.tar` | `tar xvf file.tar`
`file.tgz` | `tar xvzf file.tgz`
`file.tar.gz` | `tar xvzf file.tar.gz`
`file.tar.bz` | `bzip -cd file.bz | tar xvf -`
`file.tar.bz2` | `tar xvjf file.tar.bz2` `bzip2 -cd file.bz2 | tar xvf -`
`file.tar.xz` | `tar xvJf file.tar.xz` `xz -cd file.xz | tar xvf -`

The construction of some of these tar arguments may be considered legacy, but they are still useful when performing specific operations. See tar(1) for details.

## which

which shows the full path of shell commands. In the following example the full path of `ssh` is used as an argument for `journalctl`:

    # journalctl $(which sshd)

## wipefs

wipefs can list or erase file system, RAID or partition-table signatures (magic strings) from the specified device. It does not erase the file systems themselves nor any other data from the device.

See wipefs(8) for more information.

For example, to erase all signatures from the device `/dev/sdb` and create a signature backup `~/wipefs-sdb-offset.bak` file for each signature:

    # wipefs --all --backup /dev/sdb

## Veja também

- A sampling of coreutils , part 2 , part 3 - Overview of commands in coreutils
- GNU Coreutils online documentation
- Learn the DD command

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