Version : 2024.01
Dernière mise-à-jour : 2024/04/28 15:08
Les commandes externes au shell sont des binaires exécutables ou des scripts, généralement situés dans /bin, /sbin, /usr/bin ou /usr/sbin :
[root@centos8 ~]# type ifconfig ifconfig is /usr/sbin/ifconfig
L'aide d'une commande externe au shell peut être visualisée dans la plupart des cas en passant le paramètre - -help en argument à la commande en question :
[root@centos8 ~]# ifconfig --help
Usage:
ifconfig [-a] [-v] [-s] <interface> [[<AF>] <address>]
[add <address>[/<prefixlen>]]
[del <address>[/<prefixlen>]]
[[-]broadcast [<address>]] [[-]pointopoint [<address>]]
[netmask <address>] [dstaddr <address>] [tunnel <address>]
[outfill <NN>] [keepalive <NN>]
[hw <HW> <address>] [mtu <NN>]
[[-]trailers] [[-]arp] [[-]allmulti]
[multicast] [[-]promisc]
[mem_start <NN>] [io_addr <NN>] [irq <NN>] [media <type>]
[txqueuelen <NN>]
[[-]dynamic]
[up|down] ...
<HW>=Hardware Type.
List of possible hardware types:
loop (Local Loopback) slip (Serial Line IP) cslip (VJ Serial Line IP)
slip6 (6-bit Serial Line IP) cslip6 (VJ 6-bit Serial Line IP) adaptive (Adaptive Serial Line IP)
ash (Ash) ether (Ethernet) ax25 (AMPR AX.25)
netrom (AMPR NET/ROM) rose (AMPR ROSE) tunnel (IPIP Tunnel)
ppp (Point-to-Point Protocol) hdlc ((Cisco)-HDLC) lapb (LAPB)
arcnet (ARCnet) dlci (Frame Relay DLCI) frad (Frame Relay Access Device)
sit (IPv6-in-IPv4) fddi (Fiber Distributed Data Interface) hippi (HIPPI)
irda (IrLAP) x25 (generic X.25) infiniband (InfiniBand)
eui64 (Generic EUI-64)
<AF>=Address family. Default: inet
List of possible address families:
unix (UNIX Domain) inet (DARPA Internet) inet6 (IPv6)
ax25 (AMPR AX.25) netrom (AMPR NET/ROM) rose (AMPR ROSE)
ipx (Novell IPX) ddp (Appletalk DDP) ash (Ash)
x25 (CCITT X.25)
Les commandes internes au shell sont des commandes telles type, cd ou umask. Pour vérifier le type de commande, il faut utiliser la commande type :
[root@centos8 ~]# type type type is a shell builtin
Le shell possède la commande help. Utilisée seule, cette commande fournit la liste des commandes internes :
[root@centos8 ~]# help
GNU bash, version 4.4.19(1)-release (x86_64-redhat-linux-gnu)
These shell commands are defined internally. Type `help' to see this list.
Type `help name' to find out more about the function `name'.
Use `info bash' to find out more about the shell in general.
Use `man -k' or `info' to find out more about commands not in this list.
A star (*) next to a name means that the command is disabled.
job_spec [&] history [-c] [-d offset] [n] or history -anrw [filename] or history -ps arg [arg...]
(( expression )) if COMMANDS; then COMMANDS; [ elif COMMANDS; then COMMANDS; ]... [ else COMMANDS; ] fi
. filename [arguments] jobs [-lnprs] [jobspec ...] or jobs -x command [args]
: kill [-s sigspec | -n signum | -sigspec] pid | jobspec ... or kill -l [sigspec]
[ arg... ] let arg [arg ...]
[[ expression ]] local [option] name[=value] ...
alias [-p] [name[=value] ... ] logout [n]
bg [job_spec ...] mapfile [-d delim] [-n count] [-O origin] [-s count] [-t] [-u fd] [-C callback] [-c quantum] >
bind [-lpsvPSVX] [-m keymap] [-f filename] [-q name] [-u name] [-r keyseq] [-x keyseq:shell-co> popd [-n] [+N | -N]
break [n] printf [-v var] format [arguments]
builtin [shell-builtin [arg ...]] pushd [-n] [+N | -N | dir]
caller [expr] pwd [-LP]
case WORD in [PATTERN [| PATTERN]...) COMMANDS ;;]... esac read [-ers] [-a array] [-d delim] [-i text] [-n nchars] [-N nchars] [-p prompt] [-t timeout] >
cd [-L|[-P [-e]] [-@]] [dir] readarray [-n count] [-O origin] [-s count] [-t] [-u fd] [-C callback] [-c quantum] [array]
command [-pVv] command [arg ...] readonly [-aAf] [name[=value] ...] or readonly -p
compgen [-abcdefgjksuv] [-o option] [-A action] [-G globpat] [-W wordlist] [-F function] [-C > return [n]
complete [-abcdefgjksuv] [-pr] [-DE] [-o option] [-A action] [-G globpat] [-W wordlist] [-F f> select NAME [in WORDS ... ;] do COMMANDS; done
compopt [-o|+o option] [-DE] [name ...] set [-abefhkmnptuvxBCHP] [-o option-name] [--] [arg ...]
continue [n] shift [n]
coproc [NAME] command [redirections] shopt [-pqsu] [-o] [optname ...]
declare [-aAfFgilnrtux] [-p] [name[=value] ...] source filename [arguments]
dirs [-clpv] [+N] [-N] suspend [-f]
disown [-h] [-ar] [jobspec ... | pid ...] test [expr]
echo [-neE] [arg ...] time [-p] pipeline
enable [-a] [-dnps] [-f filename] [name ...] times
eval [arg ...] trap [-lp] [[arg] signal_spec ...]
exec [-cl] [-a name] [command [arguments ...]] [redirection ...] true
exit [n] type [-afptP] name [name ...]
export [-fn] [name[=value] ...] or export -p typeset [-aAfFgilnrtux] [-p] name[=value] ...
false ulimit [-SHabcdefiklmnpqrstuvxPT] [limit]
fc [-e ename] [-lnr] [first] [last] or fc -s [pat=rep] [command] umask [-p] [-S] [mode]
fg [job_spec] unalias [-a] name [name ...]
for NAME [in WORDS ... ] ; do COMMANDS; done unset [-f] [-v] [-n] [name ...]
for (( exp1; exp2; exp3 )); do COMMANDS; done until COMMANDS; do COMMANDS; done
function name { COMMANDS ; } or name () { COMMANDS ; } variables - Names and meanings of some shell variables
getopts optstring name [arg] wait [-n] [id ...]
hash [-lr] [-p pathname] [-dt] [name ...] while COMMANDS; do COMMANDS; done
help [-dms] [pattern ...] { COMMANDS ; }
L'aide concernant une commande spécifique peut être obtenu en passant la commande concernée en argument à la commande help :
[root@centos8 ~]# help type
type: type [-afptP] name [name ...]
Display information about command type.
For each NAME, indicate how it would be interpreted if used as a
command name.
Options:
-a display all locations containing an executable named NAME;
includes aliases, builtins, and functions, if and only if
the `-p' option is not also used
-f suppress shell function lookup
-P force a PATH search for each NAME, even if it is an alias,
builtin, or function, and returns the name of the disk file
that would be executed
-p returns either the name of the disk file that would be executed,
or nothing if `type -t NAME' would not return `file'
-t output a single word which is one of `alias', `keyword',
`function', `builtin', `file' or `', if NAME is an alias,
shell reserved word, shell function, shell builtin, disk file,
or not found, respectively
Arguments:
NAME Command name to be interpreted.
Exit Status:
Returns success if all of the NAMEs are found; fails if any are not found.
La commande man donne accès au manuel de la commande passée en argument. Par exemple man passwd :
[root@centos8 ~]# man passwd
BASH_BUILTINS(1) General Commands Manual BASH_BUILTINS(1)
NAME
bash, :, ., [, alias, bg, bind, break, builtin, caller, cd, command, compgen, complete, compopt, continue, declare, dirs, disown, echo, enable, eval, exec, exit, export, false, fc,
fg, getopts, hash, help, history, jobs, kill, let, local, logout, mapfile, popd, printf, pushd, pwd, read, readonly, return, set, shift, shopt, source, suspend, test, times, trap,
true, type, typeset, ulimit, umask, unalias, unset, wait - bash built-in commands, see bash(1)
BASH BUILTIN COMMANDS
Unless otherwise noted, each builtin command documented in this section as accepting options preceded by - accepts -- to signify the end of the options. The :, true, false, and test
builtins do not accept options and do not treat -- specially. The exit, logout, return, break, continue, let, and shift builtins accept and process arguments beginning with - with‐
out requiring --. Other builtins that accept arguments but are not specified as accepting options interpret arguments beginning with - as invalid options and require -- to prevent
this interpretation.
: [arguments]
No effect; the command does nothing beyond expanding arguments and performing any specified redirections. The return status is zero.
. filename [arguments]
source filename [arguments]
Read and execute commands from filename in the current shell environment and return the exit status of the last command executed from filename. If filename does not contain a
slash, filenames in PATH are used to find the directory containing filename. The file searched for in PATH need not be executable. When bash is not in posix mode, the cur‐
rent directory is searched if no file is found in PATH. If the sourcepath option to the shopt builtin command is turned off, the PATH is not searched. If any arguments are
supplied, they become the positional parameters when filename is executed. Otherwise the positional parameters are unchanged. If the -T option is enabled, source inherits
any trap on DEBUG; if it is not, any DEBUG trap string is saved and restored around the call to source, and source unsets the DEBUG trap while it executes. If -T is not set,
and the sourced file changes the DEBUG trap, the new value is retained when source completes. The return status is the status of the last command exited within the script (0
if no commands are executed), and false if filename is not found or cannot be read.
alias [-p] [name[=value] ...]
Alias with no arguments or with the -p option prints the list of aliases in the form alias name=value on standard output. When arguments are supplied, an alias is defined for
each name whose value is given. A trailing space in value causes the next word to be checked for alias substitution when the alias is expanded. For each name in the argument
list for which no value is supplied, the name and value of the alias is printed. Alias returns true unless a name is given for which no alias has been defined.
bg [jobspec ...]
Resume each suspended job jobspec in the background, as if it had been started with &. If jobspec is not present, the shell's notion of the current job is used. bg jobspec
returns 0 unless run when job control is disabled or, when run with job control enabled, any specified jobspec was not found or was started without job control.
bind [-m keymap] [-lpsvPSVX]
bind [-m keymap] [-q function] [-u function] [-r keyseq]
bind [-m keymap] -f filename
bind [-m keymap] -x keyseq:shell-command
bind [-m keymap] keyseq:function-name
bind [-m keymap] keyseq:readline-command
Display current readline key and function bindings, bind a key sequence to a readline function or macro, or set a readline variable. Each non-option argument is a command as
it would appear in .inputrc, but each binding or command must be passed as a separate argument; e.g., '"\C-x\C-r": re-read-init-file'. Options, if supplied, have the follow‐
Manual page help(1) line 1 (press h for help or q to quit)
Une page de manuel peut contenir plusieurs sections :
| Section | Contenu |
|---|---|
| NOM | Nom et rôle de la commande |
| SYNOPSIS | Syntaxe de la commande, paramètres et arguments |
| DESCRIPTION | Mode d'emploi et les arguments principaux |
| OPTIONS | Descriptions détaillées de chaque paramètre |
| EXEMPLES / EXAMPLES | Exemples d'utilisation de la commande |
| ENVIRONNEMENT / ENVIRONMENT VARIABLES | Fonctionnement selon l'environnement du shell |
| CONFORMITÉ / STANDARDS / CONFORMING TO | Éventuelles normes auxquelles la commande se conforme |
| BOGUES / BUGS/TO DO | Éventuelles bogues connues |
| DIAGNOSTICS/RETOUR / EXIT STATUS/RETURN VALUE | Codes d'erreur et leur signification |
| VOIR AUSSI / SEE ALSO | Commandes liées à celle du manuel actuel |
La navigation dans la page de manuel se fait grâce à l'utilisation de certaines touches :
| Touche | Fonction |
|---|---|
| Espace | Faire défiler une page complète |
| Entrée | Faire défiler la page ligne par ligne |
| ↑ | Faire défiler la page une ligne vers le haut |
| ↓ | Faire défiler la page une ligne vers le bas |
| PageHaut | Faire défiler une demi-page vers le haut |
| PageBas | Faire défiler une demi-page vers le bas |
| Début | Se positionner au début du manuel |
| Fin | Se positionner à la fin du manuel |
| / | Rechercher la chaîne qui suit la touche /. La touche n recherche l'occurrence suivante. La touche N recherche l'occurrence précédente |
| Q | Quitter le manuel |
Un manuel complet est fait de plusieurs sections :
| Section | Contenu |
|---|---|
| 1 | Instructions exécutables ou commandes shell |
| 2 | Appels système |
| 3 | Appels des bibliothèques |
| 4 | Fichiers spéciaux |
| 5 | Format des fichiers |
| 6 | Jeux, économiseurs d'écrans, gadgets |
| 7 | Divers et commandes non standard |
| 8 | Commandes d'administration du système Linux |
| 9 | Sous-programmes du noyau |
Les différentes sections disponibles sont visibles grâce à l'utilisation de la commande whereis :
[root@centos8 ~]# whereis passwd passwd: /usr/bin/passwd /etc/passwd /usr/share/man/man1/passwd.1.gz /usr/share/man/man5/passwd.5.gz
Pour visualiser une section spécifique, il convient de préciser son numéro :
[root@centos8 ~]# man 5 passwd
PASSWD(5) Linux Programmer's Manual PASSWD(5)
NAME
passwd - password file
DESCRIPTION
The /etc/passwd file is a text file that describes user login accounts for the system. It should have read permission allowed for all users (many utilities, like ls(1) use it to map
user IDs to usernames), but write access only for the superuser.
In the good old days there was no great problem with this general read permission. Everybody could read the encrypted passwords, but the hardware was too slow to crack a well-chosen
password, and moreover the basic assumption used to be that of a friendly user-community. These days many people run some version of the shadow password suite, where /etc/passwd has
an 'x' character in the password field, and the encrypted passwords are in /etc/shadow, which is readable by the superuser only.
If the encrypted password, whether in /etc/passwd or in /etc/shadow, is an empty string, login is allowed without even asking for a password. Note that this functionality may be
intentionally disabled in applications, or configurable (for example using the "nullok" or "nonull" arguments to pam_unix.so).
If the encrypted password in /etc/passwd is "*NP*" (without the quotes), the shadow record should be obtained from an NIS+ server.
Regardless of whether shadow passwords are used, many system administrators use an asterisk (*) in the encrypted password field to make sure that this user can not authenticate him-
or herself using a password. (But see NOTES below.)
If you create a new login, first put an asterisk (*) in the password field, then use passwd(1) to set it.
Each line of the file describes a single user, and contains seven colon-separated fields:
name:password:UID:GID:GECOS:directory:shell
The field are as follows:
name This is the user's login name. It should not contain capital letters.
password This is either the encrypted user password, an asterisk (*), or the letter 'x'. (See pwconv(8) for an explanation of 'x'.)
UID The privileged root login account (superuser) has the user ID 0.
GID This is the numeric primary group ID for this user. (Additional groups for the user are defined in the system group file; see group(5)).
GECOS This field (sometimes called the "comment field") is optional and used only for informational purposes. Usually, it contains the full username. Some programs (for exam‐
ple, finger(1)) display information from this field.
GECOS stands for "General Electric Comprehensive Operating System", which was renamed to GCOS when GE's large systems division was sold to Honeywell. Dennis Ritchie has
reported: "Sometimes we sent printer output or batch jobs to the GCOS machine. The gcos field in the password file was a place to stash the information for the $IDENT‐
Manual page passwd(5) line 1 (press h for help or q to quit)
Chaque page de manuel contient une brève description. Ces descriptions ainsi que le nom du manuel sont stockés dans la base de données whatis.
Cette base de données peut être maintenue manuellement par root en invoquant l'exécutable /usr/bin/mandb.
L'utilisation de mandb est très simple :
[root@centos8 ~]# mandb Processing manual pages under /usr/share/man/overrides... Updating index cache for path `/usr/share/man/overrides/man3'. Wait...done. Checking for stray cats under /usr/share/man/overrides... Checking for stray cats under /var/cache/man/overrides... ... Processing manual pages under /usr/share/man/pt... Purging old database entries in /usr/local/share/man... Processing manual pages under /usr/local/share/man... 0 man subdirectories contained newer manual pages. 0 manual pages were added. 0 stray cats were added. 17 old database entries were purged.
La commande whatis peut maintenant être utilisée pour identifier les sections des manuels disponibles pour une commande donnée :
[root@centos8 ~]# whatis passwd openssl-passwd (1ssl) - compute password hashes passwd (1) - update user's authentication tokens passwd (5) - password file
La commande apropos cherche dans la base de données whatis la chaine de caractères passée en argument à la commande. Sans option, la sortie obtenue est identique à la commande man -k :
[root@centos8 ~]# apropos passwd chgpasswd (8) - update group passwords in batch mode chpasswd (8) - update passwords in batch mode fgetpwent_r (3) - get passwd file entry reentrantly getpwent_r (3) - get passwd file entry reentrantly gpasswd (1) - administer /etc/group and /etc/gshadow grub2-mkpasswd-pbkdf2 (1) - Generate a PBKDF2 password hash. lpasswd (1) - Change group or user password openssl-passwd (1ssl) - compute password hashes pam_localuser (8) - require users to be listed in /etc/passwd passwd (1) - update user's authentication tokens passwd (5) - password file passwd2des (3) - RFS password encryption pwhistory_helper (8) - Helper binary that transfers password hashes from passwd or shadow to opasswd smbpasswd (5) - The Samba encrypted password file sslpasswd (1ssl) - compute password hashes
Le résultat est une liste de commandes suivies par une description brève de celles-ci.
Important - Notez que les numéros entre parenthèses indiquent les sections disponibles.
En plus du système des manuels, des informations concernant des exécutables peuvent être trouvées dans le système info. De l'information détaillée, des exemples et des tutoriels peuvent être absents du système des manuels. Pour cette raison le système info a été créé.
Dans le système info, de multiples pages d'informations concernant un exécutable, appelées nœuds, sont regroupées. La navigation entre nœuds est simple et utilise un système de liens hypertexte.
Afin de faciliter la navigation chaque page contient une entête qui inclut de l'information sur le nœud courant, le nœud parent, le nœud précédent et le nœud suivant. Pour naviguer entre les nœuds il convient d'utiliser les touches suivantes :
| Touch | Fonction |
|---|---|
| n | Nœud suivant. |
| p | Nœud précédent. |
| u | Nœud parent. |
| Espace | Défiler une page vers le bas. |
| Suppr | Défiler une page vers le haut. |
| b | Retour au début du nœud courant. |
| Tab ⇆ | Sélectionner le lien hypertexte suivant. |
| m <lien> | Aller au sous-nœud spécifié. En appuyant sur [Tab], on obtient la liste de tous les sous-nœuds. |
| ↵ Entrée | Suivre le lien hypertexte courant. Un lien hypertexte commence avec un astérisque et se termine avec le caractère :. |
| q | Quitter le système info. |
Pour accéder au premier nœud, utilisez la commande suivante :
[root@centos8 ~]# info
...
File: dir, Node: Top, This is the top of the INFO tree.
This is the Info main menu (aka directory node).
A few useful Info commands:
'q' quits;
'H' lists all Info commands;
'h' starts the Info tutorial;
'mTexinfo RET' visits the Texinfo manual, etc.
* Menu:
Archiving
* Cpio: (cpio). Copy-in-copy-out archiver to tape or disk.
* Tar: (tar). Making tape (or disk) archives.
Basics
* Bash: (bash). The GNU Bourne-Again SHell.
* Common options: (coreutils)Common options.
* Coreutils: (coreutils). Core GNU (file, text, shell) utilities.
* Date input formats: (coreutils)Date input formats.
* Ed: (ed). The GNU line editor
* File permissions: (coreutils)File permissions.
Access modes.
* Finding files: (find). Operating on files matching certain criteria.
* time: (time). GNU time Utility
Compression
-----Info: (dir)Top, 307 lines --Top------------------------------------------------------------------------------
Welcome to Info version 6.5. Type H for help, h for tutorial.
Copyright © 2024 Hugh Norris.