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Diffstat (limited to 'doc/manual/src/command-ref/opt-common.md')
| -rw-r--r-- | doc/manual/src/command-ref/opt-common.md | 84 |
1 files changed, 42 insertions, 42 deletions
diff --git a/doc/manual/src/command-ref/opt-common.md b/doc/manual/src/command-ref/opt-common.md index b9c65c81d..ee8419fd2 100644 --- a/doc/manual/src/command-ref/opt-common.md +++ b/doc/manual/src/command-ref/opt-common.md @@ -71,35 +71,34 @@ Most Nix commands accept the following command-line options: - `--max-jobs` / `-j` *number* Sets the maximum number of build jobs that Nix will perform in parallel to the specified number. Specify `auto` to use the number - of CPUs in the system. The default is specified by the - [`max-jobs`](#conf-max-jobs) configuration setting, which itself - defaults to `1`. A higher value is useful on SMP systems or to - exploit I/O latency. + of CPUs in the system. The default is specified by the `max-jobs` + configuration setting, which itself defaults to `1`. A higher + value is useful on SMP systems or to exploit I/O latency. Setting it to `0` disallows building on the local machine, which is useful when you want builds to happen only on remote builders. - `--cores` - Sets the value of the `NIX_BUILD_CORES` environment variable in the - invocation of builders. Builders can use this variable at their - discretion to control the maximum amount of parallelism. For + Sets the value of the `NIX_BUILD_CORES` environment variable in + the invocation of builders. Builders can use this variable at + their discretion to control the maximum amount of parallelism. For instance, in Nixpkgs, if the derivation attribute `enableParallelBuilding` is set to `true`, the builder passes the - `-jN` flag to GNU Make. It defaults to the value of the - [`cores`](#conf-cores) configuration setting, if set, or `1` - otherwise. The value `0` means that the builder should use all - available CPU cores in the system. + `-jN` flag to GNU Make. It defaults to the value of the `cores` + configuration setting, if set, or `1` otherwise. The value `0` + means that the builder should use all available CPU cores in the + system. - `--max-silent-time` Sets the maximum number of seconds that a builder can go without - producing any data on standard output or standard error. The default - is specified by the [`max-silent-time`](#conf-max-silent-time) - configuration setting. `0` means no time-out. + producing any data on standard output or standard error. The + default is specified by the `max-silent-time` configuration + setting. `0` means no time-out. - `--timeout` Sets the maximum number of seconds that a builder can run. The - default is specified by the [`timeout`](#conf-timeout) configuration - setting. `0` means no timeout. + default is specified by the `timeout` configuration setting. `0` + means no timeout. - `--keep-going` / `-k` Keep going in case of failed builds, to the greatest extent @@ -145,16 +144,17 @@ Most Nix commands accept the following command-line options: operations will fail. - `--arg` *name* *value* - This option is accepted by `nix-env`, `nix-instantiate`, `nix-shell` - and `nix-build`. When evaluating Nix expressions, the expression - evaluator will automatically try to call functions that it - encounters. It can automatically call functions for which every - argument has a [default value](#ss-functions) (e.g., `{ argName ? - defaultValue }: - ...`). With `--arg`, you can also call functions that have arguments - without a default value (or override a default value). That is, if - the evaluator encounters a function with an argument named *name*, - it will call it with value *value*. + This option is accepted by `nix-env`, `nix-instantiate`, + `nix-shell` and `nix-build`. When evaluating Nix expressions, the + expression evaluator will automatically try to call functions that + it encounters. It can automatically call functions for which every + argument has a [default + value](../expressions/language-constructs.md#functions) (e.g., + `{ argName ? defaultValue }: ...`). With `--arg`, you can also + call functions that have arguments without a default value (or + override a default value). That is, if the evaluator encounters a + function with an argument named *name*, it will call it with value + *value*. For instance, the top-level `default.nix` in Nixpkgs is actually a function: @@ -165,28 +165,28 @@ Most Nix commands accept the following command-line options: }: ... So if you call this Nix expression (e.g., when you do `nix-env -i - pkgname`), the function will be called automatically using the value - [`builtins.currentSystem`](#builtin-currentSystem) for the `system` - argument. You can override this using `--arg`, e.g., `nix-env -i - pkgname --arg system - \"i686-freebsd\"`. (Note that since the argument is a Nix string - literal, you have to escape the quotes.) + pkgname`), the function will be called automatically using the + value [`builtins.currentSystem`](../expressions/builtins.md) for + the `system` argument. You can override this using `--arg`, e.g., + `nix-env -i pkgname --arg system \"i686-freebsd\"`. (Note that + since the argument is a Nix string literal, you have to escape the + quotes.) - `--argstr` *name* *value* - This option is like `--arg`, only the value is not a Nix expression - but a string. So instead of `--arg system \"i686-linux\"` (the outer - quotes are to keep the shell happy) you can say `--argstr system - i686-linux`. + This option is like `--arg`, only the value is not a Nix + expression but a string. So instead of `--arg system + \"i686-linux\"` (the outer quotes are to keep the shell happy) you + can say `--argstr system i686-linux`. - `--attr` / `-A` *attrPath* Select an attribute from the top-level Nix expression being evaluated. (`nix-env`, `nix-instantiate`, `nix-build` and - `nix-shell` only.) The *attribute path* *attrPath* is a sequence of - attribute names separated by dots. For instance, given a top-level - Nix expression *e*, the attribute path `xorg.xorgserver` would cause - the expression `e.xorg.xorgserver` to be used. See [`nix-env - --install`](#refsec-nix-env-install-examples) for some concrete - examples. + `nix-shell` only.) The *attribute path* *attrPath* is a sequence + of attribute names separated by dots. For instance, given a + top-level Nix expression *e*, the attribute path `xorg.xorgserver` + would cause the expression `e.xorg.xorgserver` to be used. See + [`nix-env --install`](nix-env.md#operation---install) for some + concrete examples. In addition to attribute names, you can also specify array indices. For instance, the attribute path `foo.3.bar` selects the `bar` |