.\" -*- mode: troff; coding: utf-8 -*-
.TH "nix3-repl" "1" ""
.RS
.PP
\fBWarning\fR 
.br
This program is
\fB\fBexperimental\fR\fR
and its interface is subject to change.
.RE
.SH Name
.LP
\f(CRnix repl\fR - start an interactive environment for evaluating Nix expressions
.SH Synopsis
.LP
\f(CRnix repl\fR [\fIoption\fR\[u2026]] \fIinstallables\fR\[u2026]
.SH Examples
.IP "\(bu" 3
Display all special commands within the REPL:
.LP
.EX
# nix repl
nix-repl> :?
.EE
.IP "\(bu" 3
Evaluate some simple Nix expressions:
.LP
.EX
# nix repl

nix-repl> 1 + 2
3

nix-repl> map (x: x * 2) [1 2 3]
[ 2 4 6 ]
.EE
.IP "\(bu" 3
Interact with Nixpkgs in the REPL:
.LP
.EX
# nix repl --file example.nix
Loading Installable ''...
Added 3 variables.

# nix repl --expr '{a={b=3;c=4;};}'
Loading Installable ''...
Added 1 variables.

# nix repl --expr '{a={b=3;c=4;};}' a
Loading Installable ''...
Added 1 variables.

# nix repl --extra-experimental-features 'flakes' nixpkgs
Loading Installable 'flake:nixpkgs#'...
Added 5 variables.

nix-repl> legacyPackages.x86_64-linux.emacs.name
\(dqemacs-27.1\(dq

nix-repl> :q

# nix repl --expr 'import <nixpkgs>{}'

Loading Installable ''...
Added 12439 variables.

nix-repl> emacs.name
\(dqemacs-27.1\(dq

nix-repl> emacs.drvPath
\(dq/nix/store/lp0sjrhgg03y2n0l10n70rg0k7hhyz0l-emacs-27.1.drv\(dq

nix-repl> drv = runCommand \(dqhello\(dq { buildInputs = [ hello ]; } \(dqhello; hello > $out\(dq

nix-repl> :b drv
this derivation produced the following outputs:
out -> /nix/store/0njwbgwmkwls0w5dv9mpc1pq5fj39q0l-hello

nix-repl> builtins.readFile drv
\(dqHello, world!\en\(dq

nix-repl> :log drv
Hello, world!
.EE
.SH Description
.LP
This command provides an interactive environment for evaluating Nix
expressions. (REPL stands for \(oqread–eval–print loop\(cq.)
.PP
On startup, it loads the Nix expressions named \fIfiles\fR and adds them
into the lexical scope. You can load addition files using the \f(CR:l
<filename>\fR command, or reload all files using \f(CR:r\fR.
.SH Options
.IP "\(bu" 3
\fB\f(CR--stdin\fR\fR
.IP
Read installables from the standard input. No default installable applied.
.SS
Common evaluation options
.IP "\(bu" 3
\fB\f(CR--arg\fR\fR \fIname\fR \fIexpr\fR
.IP
Pass the value \fIexpr\fR as the argument \fIname\fR to Nix functions.
.IP "\(bu" 3
\fB\f(CR--arg-from-file\fR\fR \fIname\fR \fIpath\fR
.IP
Pass the contents of file \fIpath\fR as the argument \fIname\fR to Nix functions.
.IP "\(bu" 3
\fB\f(CR--arg-from-stdin\fR\fR \fIname\fR
.IP
Pass the contents of stdin as the argument \fIname\fR to Nix functions.
.IP "\(bu" 3
\fB\f(CR--argstr\fR\fR \fIname\fR \fIstring\fR
.IP
Pass the string \fIstring\fR as the argument \fIname\fR to Nix functions.
.IP "\(bu" 3
\fB\f(CR--debugger\fR\fR
.IP
Start an interactive environment if evaluation fails.
.IP "\(bu" 3
\fB\f(CR--eval-store\fR\fR \fIstore-url\fR
.IP
The \fBURL of the Nix store\fR
to use for evaluation, i.e. to store derivations (\f(CR.drv\fR files) and inputs referenced by them.
.IP "\(bu" 3
\fB\f(CR--impure\fR\fR
.IP
Allow access to mutable paths and repositories.
.IP "\(bu" 3
\fB\f(CR--include\fR\fR / \f(CR-I\fR \fIpath\fR
.IP
Add \fIpath\fR to search path entries used to resolve \fBlookup paths\fR
.IP
This option may be given multiple times.
.IP
Paths added through \f(CR-I\fR take precedence over the \fB\f(CRnix-path\fR configuration setting\fR and the \fB\f(CRNIX_PATH\fR environment variable\fR.
.IP "\(bu" 3
\fB\f(CR--override-flake\fR\fR \fIoriginal-ref\fR \fIresolved-ref\fR
.IP
Override the flake registries, redirecting \fIoriginal-ref\fR to \fIresolved-ref\fR.
.SS
Common flake-related options
.IP "\(bu" 3
\fB\f(CR--commit-lock-file\fR\fR
.IP
Commit changes to the flake\(cqs lock file.
.IP "\(bu" 3
\fB\f(CR--inputs-from\fR\fR \fIflake-url\fR
.IP
Use the inputs of the specified flake as registry entries.
.IP "\(bu" 3
\fB\f(CR--no-registries\fR\fR
.IP
Don\(cqt allow lookups in the flake registries.
.RS
.IP
\fBDEPRECATED\fR
.IP
Use \fB\f(CR--no-use-registries\fR\fR instead.
.RE
.IP "\(bu" 3
\fB\f(CR--no-update-lock-file\fR\fR
.IP
Do not allow any updates to the flake\(cqs lock file.
.IP "\(bu" 3
\fB\f(CR--no-write-lock-file\fR\fR
.IP
Do not write the flake\(cqs newly generated lock file.
.IP "\(bu" 3
\fB\f(CR--output-lock-file\fR\fR \fIflake-lock-path\fR
.IP
Write the given lock file instead of \f(CRflake.lock\fR within the top-level flake.
.IP "\(bu" 3
\fB\f(CR--override-input\fR\fR \fIinput-path\fR \fIflake-url\fR
.IP
Override a specific flake input (e.g. \f(CRdwarffs/nixpkgs\fR). This implies \f(CR--no-write-lock-file\fR.
.IP "\(bu" 3
\fB\f(CR--recreate-lock-file\fR\fR
.IP
Recreate the flake\(cqs lock file from scratch.
.RS
.IP
\fBDEPRECATED\fR
.IP
Use \fB\f(CRnix flake update\fR\fR instead.
.RE
.IP "\(bu" 3
\fB\f(CR--reference-lock-file\fR\fR \fIflake-lock-path\fR
.IP
Read the given lock file instead of \f(CRflake.lock\fR within the top-level flake.
.IP "\(bu" 3
\fB\f(CR--update-input\fR\fR \fIinput-path\fR
.IP
Update a specific flake input (ignoring its previous entry in the lock file).
.RS
.IP
\fBDEPRECATED\fR
.IP
Use \fB\f(CRnix flake update\fR\fR instead.
.RE
.SS
Logging-related options
.IP "\(bu" 3
\fB\f(CR--debug\fR\fR
.IP
Set the logging verbosity level to \(oqdebug\(cq.
.IP "\(bu" 3
\fB\f(CR--log-format\fR\fR \fIformat\fR
.IP
Set the format of log output; one of \f(CRraw\fR, \f(CRinternal-json\fR, \f(CRbar\fR or \f(CRbar-with-logs\fR.
.IP "\(bu" 3
\fB\f(CR--print-build-logs\fR\fR / \f(CR-L\fR
.IP
Print full build logs on standard error.
.IP "\(bu" 3
\fB\f(CR--quiet\fR\fR
.IP
Decrease the logging verbosity level.
.IP "\(bu" 3
\fB\f(CR--verbose\fR\fR / \f(CR-v\fR
.IP
Increase the logging verbosity level.
.SS
Miscellaneous global options
.IP "\(bu" 3
\fB\f(CR--help\fR\fR
.IP
Show usage information.
.IP "\(bu" 3
\fB\f(CR--offline\fR\fR
.IP
Disable substituters and consider all previously downloaded files up-to-date.
.IP "\(bu" 3
\fB\f(CR--option\fR\fR \fIname\fR \fIvalue\fR
.IP
Set the Nix configuration setting \fIname\fR to \fIvalue\fR (overriding \f(CRnix.conf\fR).
.IP "\(bu" 3
\fB\f(CR--refresh\fR\fR
.IP
Consider all previously downloaded files out-of-date.
.IP "\(bu" 3
\fB\f(CR--repair\fR\fR
.IP
During evaluation, rewrite missing or corrupted files in the Nix store. During building, rebuild missing or corrupted store paths.
.IP "\(bu" 3
\fB\f(CR--version\fR\fR
.IP
Show version information.
.SS
Options that change the interpretation of \fBinstallables\fR
.IP "\(bu" 3
\fB\f(CR--expr\fR\fR \fIexpr\fR
.IP
Interpret \fB\fIinstallables\fR\fR as attribute paths relative to the Nix expression \fIexpr\fR.
.IP "\(bu" 3
\fB\f(CR--file\fR\fR / \f(CR-f\fR \fIfile\fR
.IP
Interpret \fB\fIinstallables\fR\fR as attribute paths relative to the Nix expression stored in \fIfile\fR. If \fIfile\fR is the character -, then a Nix expression will be read from standard input. Implies \f(CR--impure\fR.
.RS
.LP
\fBNote\fR
.PP
See \fB\f(CRman nix.conf\fR\fR for overriding configuration settings with command line flags.
.RE