Los mejores trucos del comando fg: cuando Ctrl+Z salva tu sesión de terminal

$ ./gradlew build
> Building...

Failed to generate image: PlantUML preprocessing failed: [From <input> (line 6) ]

@startuml
skinparam backgroundColor #FEFEFE

actor Développeur as dev
participant "Terminal" as term
participant "Gradle
^^^^^
 Syntax Error? (Assumed diagram type: sequence)

@startuml
skinparam backgroundColor #FEFEFE

actor Développeur as dev
participant "Terminal" as term
participant "Gradle
( proceso )" as gradle

dev -> term : ./gradlew build
term -> gradle : Lance le build
gradle -> term : Occupe le terminal\n(pas de prompt)
dev -> term : veut taper une commande
term --> dev : ❌ Terminal bloqué

note right of dev
  Le développeur est
  paralysé pendant
  toute la durée du build
end note
@enduml

Failed to generate image: PlantUML preprocessing failed: [From <input> (line 8) ]

@startuml
skinparam backgroundColor #FEFEFE
autonumber

actor Développeur as dev
participant "Terminal" as term
participant "Gradle" as gradle
database "Estado
^^^^^
 Syntax Error? (Assumed diagram type: sequence)

@startuml
skinparam backgroundColor #FEFEFE
autonumber

actor Développeur as dev
participant "Terminal" as term
participant "Gradle" as gradle
database "Estado
proceso" as state

dev -> term : ./gradlew build
term -> gradle : Lance le build
gradle -> state : En cours (FG)
dev -> term : Ctrl+Z
term -> state : Suspendu (job [1])
term --> dev : Prompt libre $

dev -> term : git status
term --> dev : working tree clean

dev -> term : fg
term -> state : Reprend (FG)
gradle --> dev : Build réussi ✓

note right of state
  Le processus Gradle
  n'a jamais été tué
  Il reprend exactement
  où il s'était arrêté
end note
@enduml

# Dans vim, en mode commande :
:shell
$ cat /path/to/other/file.txt
$ exit
# Retour dans vim

# Dans vim, n'importe quel moment :
Ctrl+Z
[1]+  Stoppé    vim README.md

$ cat /path/to/other/file.txt
# ... lire le fichier ...

$ fg
vim README.md
# Retour exact là où on en était, curseur en place

Failed to generate image: PlantUML preprocessing failed: [From <input> (line 7) ]

@startuml
skinparam backgroundColor #FEFEFE
skinparam defaultFontName sans-serif
skinparam componentStyle rectangle

actor Développeur as dev
participant "opencode
^^^^^
 Syntax Error? (Assumed diagram type: sequence)

@startuml
skinparam backgroundColor #FEFEFE
skinparam defaultFontName sans-serif
skinparam componentStyle rectangle

actor Développeur as dev
participant "opencode
(LLM agente)" as agent
participant "Shell" as shell
participant "git" as git

dev -> agent : Session active
agent -> agent : Tour de parole\ndu LLM en cours

note over agent
  Ctrl+Z arrive
  en plein milieu
  d'une analyse de code
end note

dev -> agent : Ctrl+Z
agent -> shell : Suspendu (job [1])
dev -> git : git diff
git --> dev : changements visibles
dev -> shell : fg
shell -> agent : Reprend (job [1])
agent --> dev : Reprend exactement\nl'analyse en cours

note right of agent
  Aucune perte de contexte
  Le LLM reprend sa réponse
  exactement où il en était
end note
@enduml

$ opencode
# ... session en cours, LLM analyse le code ...
^Z
[1]+  Stoppé    opencode

$ git diff HEAD~1
# vérifier les changements récents

$ fg
opencode
# Le LLM reprend là où il s'était arrêté

$ vim config.yml
^Z
[1]+  Stoppé    vim config.yml

$ ./gradlew test
^Z
[2]+  Stoppé    ./gradlew test

$ htop
^Z
[3]+  Stoppé    htop

$ jobs
[1]   Stoppé    vim config.yml
[2]-  Stoppé    ./gradlew test
[3]+  Stoppé    htop

$ fg %2
./gradlew test
# Le build reprend en avant-plan

$ bg %3
[3] htop &
# htop reprend en arrière-plan

Failed to generate image: PlantUML preprocessing failed: [From <input> (line 10) ]

@startuml
skinparam backgroundColor #FEFEFE
skinparam defaultFontName sans-serif

rectangle "**Ctrl+Z**\nSIGTSTP" as ctrlz #LightYellow {
  card "Suspende el proceso\n(todavía está en memoria)\nUtilizable con fg/bg" as c1
}

rectangle "**Ctrl+C**
SIGINT" as ctrlc #LightCoral {
^^^^^
 Syntax Error? (Assumed diagram type: activity)

@startuml
skinparam backgroundColor #FEFEFE
skinparam defaultFontName sans-serif

rectangle "**Ctrl+Z**\nSIGTSTP" as ctrlz #LightYellow {
  card "Suspende el proceso\n(todavía está en memoria)\nUtilizable con fg/bg" as c1
}

rectangle "**Ctrl+C**
SIGINT" as ctrlc #LightCoral {
  card "Finaliza el proceso
(sin posibilidad de retorno)
Pérdida de todo el estado" as c2
}

rectangle "** & \n(fondo)" as ampersand #LightGreen {
  card "Inicia directamente
en segundo plano
Terminal libre inmediatamente" as c3
}

rectangle "**fg**\n(primer plano)" as fg_ #SkyBlue {
  card "Trae un trabajo
suspendido en primer plano
Terminal ocupado" as c4
}

rectangle "**bg**
(fondo)" as bg_ #Lavender {
  card "Reanuda un trabajo
suspendido en segundo plano
Terminal libre" as c5
}

ctrlz -right-> fg_ : fg pour reprendre
ctrlz -right-> bg_ : bg pour continuer\nen arrière-plan
ctrlc -right-> c2 : Pas de retour\nprocessus tué

note bottom of ctrlz
  Le processus est **figé**
  mais **pas tué**
end note

note bottom of ampersand
  Alternative : lancer
  ./gradlew build &
  directement en arrière-plan
end note
@enduml

Failed to generate image: PlantUML preprocessing failed: [From <input> (line 8) ]

@startuml
skinparam backgroundColor #FEFEFE
skinparam defaultFontName sans-serif

title Ciclo de vida completo de un trabajo shell
state "Inexistente" as none
state "Primer plano\n(ocupa la terminal)" as foreground #LightCoral
state "Suspendido
^^^^^
 Syntax Error? (Assumed diagram type: state)

@startuml
skinparam backgroundColor #FEFEFE
skinparam defaultFontName sans-serif

title Ciclo de vida completo de un trabajo shell
state "Inexistente" as none
state "Primer plano\n(ocupa la terminal)" as foreground #LightCoral
state "Suspendido
(Ctrl+Z / SIGTSTP)" as suspended #LightYellow
state "Fondo
(bg o &)" as background #LightGreen
state "Terminado
(exit code 0)" as done #LightGray

[*] --> none
none --> foreground : tape une commande
foreground --> suspended : Ctrl+Z
foreground --> done : fin normale

suspended --> foreground : fg
suspended --> background : bg
suspended --> done : kill %n

background --> foreground : fg
background --> done : fin normale\n(en arrière-plan)
background --> suspended : Ctrl+Z\n(si fg puis Ctrl+Z)

done --> [*]

note right of suspended
  L'état suspendu est
  le pivot de tout le
  système de jobs
end note
@enduml

Failed to generate image: PlantUML preprocessing failed: [From <input> (line 10) ]

@startuml
skinparam backgroundColor #FEFEFE
skinparam defaultFontName sans-serif
skinparam ArrowColor #444444

title "fg — El consejo que cambia todo"

rectangle "Problema" as problem #LightCoral {
  card "Terminal bloqueado
por un proceso" as p1
^^^^^
 Syntax Error? (Assumed diagram type: activity)

@startuml
skinparam backgroundColor #FEFEFE
skinparam defaultFontName sans-serif
skinparam ArrowColor #444444

title "fg — El consejo que cambia todo"

rectangle "Problema" as problem #LightCoral {
  card "Terminal bloqueado
por un proceso" as p1
  card "Abrir un nuevo
terminal = solución pesada" as p2
}

rectangle "**Solución**" as solution #LightGreen {
  card "Ctrl+Z → suspender" as s1
  card "fg → retoma" as s2
  card "bg → en segundo plano" as s3
  card "jobs → ver los suspendidos" as s4
}

rectangle "Ventajas" as advantages #SkyBlue {
  card "Sin pérdida de contexto" as a1
  card "No reinicio" as a2
  card "Un solo terminal basta" as a3
}

problem -right-> solution : "La solución nativa\nUnix desde hace 40 años"
solution -right-> advantages : "Resultado"

note bottom of advantages
  fg n'est pas un tips obscur
  C'est un mécanisme fondamental
  du shell Unix
end note
@enduml

Failed to generate image: PlantUML preprocessing failed: [From <input> (line 6) ]

@startuml
skinparam backgroundColor #FEFEFE
skinparam defaultFontName sans-serif

rectangle "¿Por qué fg está
subestimado?" as why #LightCoral {
^^^^^
 Syntax Error? (Assumed diagram type: activity)

@startuml
skinparam backgroundColor #FEFEFE
skinparam defaultFontName sans-serif

rectangle "¿Por qué fg está
subestimado?" as why #LightCoral {
  card "IDE con terminal\nmultipestañas" as w1
  card "Herramientas gráficas
que sustituyen la CLI" as w2
  card "tmux/screen
resuelven el problema
de otra manera" as w3
}

rectangle "¿Por qué fg es
superior?" as superior #LightGreen {
  card "Universal: bash,\nzsh, fish, sh..." as s1
  card "Sin dependencia:
Sin instalación" as s2
  card "Dos pulsaciones:\nCtrl+Z luego fg" as s3
  card "Contexto preservado:\ncero pérdida de estado" as s4
}

why -right-> superior : "La simplicidad
siempre gana"
@enduml