* [PATCH 1/3] var: add GIT_HOSTNAME
2026-10-12 1:58 ` [PATCH 0/3] Add hostname condition to includeIf Isabella Caselli
@ 2026-10-12 1:58 ` Isabella Caselli
2026-10-12 1:58 ` [PATCH 2/3] t6500: get hostname from "git var" Isabella Caselli
` (2 subsequent siblings)
3 siblings, 0 replies; 15+ messages in thread
From: Isabella Caselli @ 2026-10-12 1:58 UTC (permalink / raw)
To: git
Cc: Junio C Hamano, Jeff King, Eric Sunshine, Ignacio Encinas,
Isabella Caselli
Git asks the system for the name of the machine it runs on in a few
places. For example, "git gc" records it in "gc.pid" to tell whether
the gc holding the lock runs on the same machine. Users have no way
to see which name Git uses, and depending on how the system is
configured, it may be a short name ("myhost") or a fully qualified
one ("myhost.example.com").
This matters more once the config can depend on the hostname, which
a later commit adds as an includeIf condition. Without a way to see
the value Git uses, users would have to guess what to write in their
config file.
Add a GIT_HOSTNAME variable to "git var" that prints the hostname
Git sees. If the hostname can't be determined, "git var GIT_HOSTNAME"
exits with a non-zero status, and "git var -l" omits the variable
instead of failing.
An option to "git config" to show the hostname was also discussed,
but "git var" was chosen, since the hostname is not specific to
the configuration code.
The test only checks that a non-empty value is printed. The test has
no independent way to know the expected hostname, as the "hostname"
command may not agree with what Git sees on every platform. The
includeIf tests added later check that the value matches what the
configuration code uses.
Suggested-by: Eric Sunshine <sunshine@sunshineco.com>
Suggested-by: Jeff King <peff@peff.net>
Signed-off-by: Isabella Caselli <bellacaselli20@gmail.com>
---
Documentation/git-var.adoc | 3 +++
builtin/var.c | 13 +++++++++++++
t/t0007-git-var.sh | 5 +++++
3 files changed, 21 insertions(+)
diff --git a/Documentation/git-var.adoc b/Documentation/git-var.adoc
index 697c10aded..e813ab4fd2 100644
--- a/Documentation/git-var.adoc
+++ b/Documentation/git-var.adoc
@@ -84,6 +84,9 @@ endif::git-default-pager[]
`GIT_CONFIG_GLOBAL`::
The path to the global (per-user) configuration files, if any.
+`GIT_HOSTNAME`::
+ The hostname of the machine, as reported by the operating system.
+
Most path values contain only one value. However, some can contain multiple
values, which are separated by newlines, and are listed in order from highest to
lowest priority. Callers should be prepared for any such path value to contain
diff --git a/builtin/var.c b/builtin/var.c
index cc3a43cde2..b427ebd61e 100644
--- a/builtin/var.c
+++ b/builtin/var.c
@@ -115,6 +115,15 @@ static char *git_config_val_global(int ident_flag UNUSED)
return strbuf_detach(&buf, &unused);
}
+static char *hostname(int ident_flag UNUSED)
+{
+ char buf[HOST_NAME_MAX + 1];
+
+ if (xgethostname(buf, sizeof(buf)))
+ return NULL;
+ return xstrdup(buf);
+}
+
struct git_var {
const char *name;
char *(*read)(int);
@@ -166,6 +175,10 @@ static struct git_var git_vars[] = {
.read = git_config_val_global,
.multivalued = 1,
},
+ {
+ .name = "GIT_HOSTNAME",
+ .read = hostname,
+ },
{
.name = "",
.read = NULL,
diff --git a/t/t0007-git-var.sh b/t/t0007-git-var.sh
index 2b60317758..f50c62a25e 100755
--- a/t/t0007-git-var.sh
+++ b/t/t0007-git-var.sh
@@ -224,6 +224,11 @@ test_expect_success 'GIT_CONFIG_GLOBAL points to the correct location' '
)
'
+test_expect_success 'GIT_HOSTNAME is not empty' '
+ hostname=$(git var GIT_HOSTNAME) &&
+ test -n "$hostname"
+'
+
# For git var -l, we check only a representative variable;
# testing the whole output would make our test too brittle with
# respect to unrelated changes in the test suite's environment.
--
2.43.0
^ permalink raw reply related [flat|nested] 15+ messages in thread* [PATCH 2/3] t6500: get hostname from "git var"
2026-10-12 1:58 ` [PATCH 0/3] Add hostname condition to includeIf Isabella Caselli
2026-10-12 1:58 ` [PATCH 1/3] var: add GIT_HOSTNAME Isabella Caselli
@ 2026-10-12 1:58 ` Isabella Caselli
2026-10-12 19:20 ` Junio C Hamano
2026-10-12 1:58 ` [PATCH 3/3] config: learn the "hostname:" includeIf condition Isabella Caselli
2026-10-14 10:31 ` [PATCH 0/3] Add hostname condition to includeIf Jeff King
3 siblings, 1 reply; 15+ messages in thread
From: Isabella Caselli @ 2026-10-12 1:58 UTC (permalink / raw)
To: git
Cc: Junio C Hamano, Jeff King, Eric Sunshine, Ignacio Encinas,
Isabella Caselli
The test "background auto gc respects lock for all operations" simulates
a concurrent gc by writing our shell's pid and hostname to "gc.pid".
It gets the hostname from the "hostname" command, falling back to
"unknown" if the command fails.
"git gc" gets its hostname from the system and only checks whether the
pid is alive if the two hostnames match. Otherwise, it assumes the
lock belongs to a gc running on another machine. Since the test passes
in either case, a missing "hostname" command or a mismatch between
its output and the system hostname can cause the test to silently
exercise the wrong case.
Use "git var GIT_HOSTNAME" to get the same hostname as "git gc".
Keep the "unknown" fallback, which is also used by "git gc" when it
cannot determine the hostname.
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Isabella Caselli <bellacaselli20@gmail.com>
---
t/t6500-gc.sh | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/t/t6500-gc.sh b/t/t6500-gc.sh
index a7142ab815..f928089bf0 100755
--- a/t/t6500-gc.sh
+++ b/t/t6500-gc.sh
@@ -413,7 +413,7 @@ test_expect_success 'background auto gc respects lock for all operations' '
# now fake a concurrent gc that holds the lock; we can use our
# shell pid so that it looks valid.
- hostname=$(hostname || echo unknown) &&
+ hostname=$(git var GIT_HOSTNAME || echo unknown) &&
shell_pid=$$ &&
if test_have_prereq MINGW && test -f /proc/$shell_pid/winpid
then
--
2.43.0
^ permalink raw reply related [flat|nested] 15+ messages in thread
* Re: [PATCH 2/3] t6500: get hostname from "git var"
2026-10-12 1:58 ` [PATCH 2/3] t6500: get hostname from "git var" Isabella Caselli
@ 2026-10-12 19:20 ` Junio C Hamano
2026-10-13 1:14 ` Isabella Caselli
0 siblings, 1 reply; 15+ messages in thread
From: Junio C Hamano @ 2026-10-12 19:20 UTC (permalink / raw)
To: Isabella Caselli; +Cc: git, Jeff King, Eric Sunshine, Ignacio Encinas
Isabella Caselli <bellacaselli20@gmail.com> writes:
> The test "background auto gc respects lock for all operations" simulates
> a concurrent gc by writing our shell's pid and hostname to "gc.pid".
> It gets the hostname from the "hostname" command, falling back to
> "unknown" if the command fails.
>
> "git gc" gets its hostname from the system and only checks whether the
> pid is alive if the two hostnames match. Otherwise, it assumes the
> lock belongs to a gc running on another machine. Since the test passes
> in either case, a missing "hostname" command or a mismatch between
> its output and the system hostname can cause the test to silently
> exercise the wrong case.
"exercise the wrong case", meaning... where hostname(1) output is
different from "git var GIT_HOSTNAME" (aka xgethostname()), we would
have written bogus name in .git/gc.pid file, simulating the case where
gc.pid was written by a process running on a different machine.
What is the implications of doing so?
>
> Use "git var GIT_HOSTNAME" to get the same hostname as "git gc".
> Keep the "unknown" fallback, which is also used by "git gc" when it
> cannot determine the hostname.
>
> Helped-by: Jeff King <peff@peff.net>
> Signed-off-by: Isabella Caselli <bellacaselli20@gmail.com>
> ---
> t/t6500-gc.sh | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/t/t6500-gc.sh b/t/t6500-gc.sh
> index a7142ab815..f928089bf0 100755
> --- a/t/t6500-gc.sh
> +++ b/t/t6500-gc.sh
> @@ -413,7 +413,7 @@ test_expect_success 'background auto gc respects lock for all operations' '
>
> # now fake a concurrent gc that holds the lock; we can use our
> # shell pid so that it looks valid.
> - hostname=$(hostname || echo unknown) &&
> + hostname=$(git var GIT_HOSTNAME || echo unknown) &&
> shell_pid=$$ &&
> if test_have_prereq MINGW && test -f /proc/$shell_pid/winpid
> then
^ permalink raw reply [flat|nested] 15+ messages in thread
* Re: [PATCH 2/3] t6500: get hostname from "git var"
2026-10-12 19:20 ` Junio C Hamano
@ 2026-10-13 1:14 ` Isabella Caselli
2026-10-13 1:43 ` Junio C Hamano
0 siblings, 1 reply; 15+ messages in thread
From: Isabella Caselli @ 2026-10-13 1:14 UTC (permalink / raw)
To: Junio C Hamano; +Cc: git, Jeff King, Eric Sunshine, Ignacio Encinas
Junio C Hamano <gitster@pobox.com> writes:
> "exercise the wrong case", meaning... where hostname(1) output is
> different from "git var GIT_HOSTNAME" (aka xgethostname()), we would
> have written bogus name in .git/gc.pid file, simulating the case where
> gc.pid was written by a process running on a different machine.
>
> What is the implications of doing so?
If the hostnames differ, lock_repo_for_gc() assumes the lock belongs
to a process on another machine. In that case, strcmp(locking_host,
my_host) is already true, so the remaining conditions are never
evaluated, such as !kill(pid, 0).
So the test would still pass, but wouldn't actually check whether Git
detects that the pid belongs to a running process on the same machine,
which is the behavior it is meant to verify.
Should I adjust the commit message to clarify this?
^ permalink raw reply [flat|nested] 15+ messages in thread
* Re: [PATCH 2/3] t6500: get hostname from "git var"
2026-10-13 1:14 ` Isabella Caselli
@ 2026-10-13 1:43 ` Junio C Hamano
0 siblings, 0 replies; 15+ messages in thread
From: Junio C Hamano @ 2026-10-13 1:43 UTC (permalink / raw)
To: Isabella Caselli; +Cc: git, Jeff King, Eric Sunshine, Ignacio Encinas
Isabella Caselli <bellacaselli20@gmail.com> writes:
> Junio C Hamano <gitster@pobox.com> writes:
>
>> "exercise the wrong case", meaning... where hostname(1) output is
>> different from "git var GIT_HOSTNAME" (aka xgethostname()), we would
>> have written bogus name in .git/gc.pid file, simulating the case where
>> gc.pid was written by a process running on a different machine.
>>
>> What is the implications of doing so?
>
> If the hostnames differ, lock_repo_for_gc() assumes the lock belongs
> to a process on another machine. In that case, strcmp(locking_host,
> my_host) is already true, so the remaining conditions are never
> evaluated, such as !kill(pid, 0).
> So the test would still pass, but wouldn't actually check whether Git
> detects that the pid belongs to a running process on the same machine,
> which is the behavior it is meant to verify.
>
> Should I adjust the commit message to clarify this?
Absolutely. The only reason I asked was because I didn't understand
what you wanted to say in the proposed log message, which means it
is very likely other people would have difficulty reading "git log"
if we committed it as-is.
Thanks.
^ permalink raw reply [flat|nested] 15+ messages in thread
* [PATCH 3/3] config: learn the "hostname:" includeIf condition
2026-10-12 1:58 ` [PATCH 0/3] Add hostname condition to includeIf Isabella Caselli
2026-10-12 1:58 ` [PATCH 1/3] var: add GIT_HOSTNAME Isabella Caselli
2026-10-12 1:58 ` [PATCH 2/3] t6500: get hostname from "git var" Isabella Caselli
@ 2026-10-12 1:58 ` Isabella Caselli
2026-10-12 19:24 ` Junio C Hamano
2026-10-14 10:31 ` [PATCH 0/3] Add hostname condition to includeIf Jeff King
3 siblings, 1 reply; 15+ messages in thread
From: Isabella Caselli @ 2026-10-12 1:58 UTC (permalink / raw)
To: git
Cc: Junio C Hamano, Jeff King, Eric Sunshine, Ignacio Encinas,
Isabella Caselli
When the same home directory is shared across multiple machines, they
all read the same ~/.gitconfig. Settings that should differ between
machines therefore need a way to make that file behave differently
on each host. The same problem affects people who keep their dotfiles
in a repository and check them out on multiple machines.
Add a "hostname:" keyword to includeIf. The value that follows is a
pattern supporting standard glob wildcards, and the condition is met
when the machine's hostname matches it. If the hostname cannot be
determined, the condition is not met.
Depending on the system configuration, the hostname may be either a
short name or a fully qualified domain name. Making the name fully
qualified ourselves was considered, but it could require a DNS lookup
while reading the configuration. Instead, match the name as the
system reports it, document this, and point to "git var GIT_HOSTNAME"
as a way to check the value being matched.
The tests obtain the hostname with "git var GIT_HOSTNAME" before
writing the configuration, so that a failure to retrieve it makes
the test fail instead of going unnoticed inside the here-document.
Based-on-patch-by: Ignacio Encinas <ignacio@iencinas.com>
Signed-off-by: Isabella Caselli <bellacaselli20@gmail.com>
---
Documentation/config.adoc | 14 ++++++++++++
Documentation/git-var.adoc | 2 ++
config.c | 17 +++++++++++++++
t/t1305-config-include.sh | 44 ++++++++++++++++++++++++++++++++++++++
4 files changed, 77 insertions(+)
diff --git a/Documentation/config.adoc b/Documentation/config.adoc
index f67dcd2f8e..aa6360e230 100644
--- a/Documentation/config.adoc
+++ b/Documentation/config.adoc
@@ -232,6 +232,16 @@ As for the naming of this keyword, it is for forwards compatibility with
a naming scheme that supports more variable-based include conditions,
but currently Git only supports the exact keyword described above.
+`hostname`::
+ The data that follows the keyword `hostname:` is taken to be a
+ pattern with standard globbing wildcards. If the hostname of
+ the machine matches the pattern, the include condition is met.
++
+Depending on how your system is configured, the hostname used for
+matching may be short (e.g., "myhost") or a fully qualified domain
+name ("myhost.example.com"). Run `git var GIT_HOSTNAME` to see the
+hostname Git uses (see linkgit:git-var[1]).
+
A few more notes on matching via `gitdir` and `gitdir/i`:
* Symlinks in `$GIT_DIR` are not resolved before matching.
@@ -315,6 +325,10 @@ Example
path = foo.inc
[remote "origin"]
url = https://example.com/git
+
+; include only if the hostname of the machine matches some-hostname
+[includeIf "hostname:some-hostname"]
+ path = foo.inc
----
Values
diff --git a/Documentation/git-var.adoc b/Documentation/git-var.adoc
index e813ab4fd2..fc2def16d3 100644
--- a/Documentation/git-var.adoc
+++ b/Documentation/git-var.adoc
@@ -86,6 +86,8 @@ endif::git-default-pager[]
`GIT_HOSTNAME`::
The hostname of the machine, as reported by the operating system.
+ This is the hostname matched by `includeIf "hostname:..."` (see
+ linkgit:git-config[1]).
Most path values contain only one value. However, some can contain multiple
values, which are separated by newlines, and are listed in order from highest to
diff --git a/config.c b/config.c
index e0bb29b53d..c891f63e60 100644
--- a/config.c
+++ b/config.c
@@ -316,6 +316,21 @@ static int include_by_branch(struct config_include_data *data,
return ret;
}
+static int include_by_hostname(const char *cond, size_t cond_len)
+{
+ int ret;
+ char my_host[HOST_NAME_MAX + 1];
+ char *pattern;
+
+ if (xgethostname(my_host, sizeof(my_host)))
+ return 0;
+
+ pattern = xmemdupz(cond, cond_len);
+ ret = !wildmatch(pattern, my_host, 0);
+ free(pattern);
+ return ret;
+}
+
static int add_remote_url(const char *var, const char *value,
const struct config_context *ctx UNUSED, void *data)
{
@@ -411,6 +426,8 @@ static int include_condition_is_true(const struct key_value_info *kvi,
else if (skip_prefix_mem(cond, cond_len, "hasconfig:remote.*.url:", &cond,
&cond_len))
return include_by_remote_url(inc, cond, cond_len);
+ else if (skip_prefix_mem(cond, cond_len, "hostname:", &cond, &cond_len))
+ return include_by_hostname(cond, cond_len);
/* unknown conditionals are always false */
return 0;
diff --git a/t/t1305-config-include.sh b/t/t1305-config-include.sh
index 507b8ebd06..01069237ba 100755
--- a/t/t1305-config-include.sh
+++ b/t/t1305-config-include.sh
@@ -524,4 +524,48 @@ test_expect_success 'conditional include, worktree without repository but explic
test_must_fail nongit git --git-dir=nonexistent config get foo.bar
'
+test_expect_success 'conditional include, hostname' '
+ hostname=$(git var GIT_HOSTNAME) &&
+ cat >>.git/config <<-EOF &&
+ [includeIf "hostname:${hostname}a"]
+ path = bar12
+ EOF
+ cat >>.git/bar12 <<-EOF &&
+ [test]
+ twelve=12
+ EOF
+
+ test_must_fail git config test.twelve &&
+
+ cat >>.git/config <<-EOF &&
+ [includeIf "hostname:$hostname"]
+ path = bar12
+ EOF
+ echo 12 >expect &&
+ git config test.twelve >actual &&
+ test_cmp expect actual
+'
+
+test_expect_success 'conditional include, hostname, wildcard' '
+ hostname=$(git var GIT_HOSTNAME) &&
+ cat >>.git/config <<-EOF &&
+ [includeIf "hostname:${hostname}a*"]
+ path = bar13
+ EOF
+ cat >>.git/bar13 <<-EOF &&
+ [test]
+ thirteen = 13
+ EOF
+
+ test_must_fail git config test.thirteen &&
+
+ cat >>.git/config <<-EOF &&
+ [includeIf "hostname:$hostname*"]
+ path = bar13
+ EOF
+ echo 13 >expect &&
+ git config test.thirteen >actual &&
+ test_cmp expect actual
+'
+
test_done
--
2.43.0
^ permalink raw reply related [flat|nested] 15+ messages in thread* Re: [PATCH 3/3] config: learn the "hostname:" includeIf condition
2026-10-12 1:58 ` [PATCH 3/3] config: learn the "hostname:" includeIf condition Isabella Caselli
@ 2026-10-12 19:24 ` Junio C Hamano
0 siblings, 0 replies; 15+ messages in thread
From: Junio C Hamano @ 2026-10-12 19:24 UTC (permalink / raw)
To: Isabella Caselli; +Cc: git, Jeff King, Eric Sunshine, Ignacio Encinas
Isabella Caselli <bellacaselli20@gmail.com> writes:
> +static int include_by_hostname(const char *cond, size_t cond_len)
> +{
> + int ret;
> + char my_host[HOST_NAME_MAX + 1];
> + char *pattern;
> +
> + if (xgethostname(my_host, sizeof(my_host)))
> + return 0;
> +
> + pattern = xmemdupz(cond, cond_len);
> + ret = !wildmatch(pattern, my_host, 0);
> + free(pattern);
> + return ret;
> +}
> +
> static int add_remote_url(const char *var, const char *value,
> const struct config_context *ctx UNUSED, void *data)
> {
> @@ -411,6 +426,8 @@ static int include_condition_is_true(const struct key_value_info *kvi,
> else if (skip_prefix_mem(cond, cond_len, "hasconfig:remote.*.url:", &cond,
> &cond_len))
> return include_by_remote_url(inc, cond, cond_len);
> + else if (skip_prefix_mem(cond, cond_len, "hostname:", &cond, &cond_len))
> + return include_by_hostname(cond, cond_len);
Neat. With this include_condition_is_true() helper, adding such
conditional inclusion is made very easy. Quite nice.
^ permalink raw reply [flat|nested] 15+ messages in thread
* Re: [PATCH 0/3] Add hostname condition to includeIf
2026-10-12 1:58 ` [PATCH 0/3] Add hostname condition to includeIf Isabella Caselli
` (2 preceding siblings ...)
2026-10-12 1:58 ` [PATCH 3/3] config: learn the "hostname:" includeIf condition Isabella Caselli
@ 2026-10-14 10:31 ` Jeff King
3 siblings, 0 replies; 15+ messages in thread
From: Jeff King @ 2026-10-14 10:31 UTC (permalink / raw)
To: Isabella Caselli; +Cc: git, Junio C Hamano, Eric Sunshine, Ignacio Encinas
On Sun, Oct 11, 2026 at 10:58:43PM -0300, Isabella Caselli wrote:
> This series adds a "hostname:" condition to includeIf, allowing a
> configuration file to be included only on machines whose hostname
> matches a pattern. It also adds GIT_HOSTNAME to "git var", so users
> can see which hostname Git uses for matching.
>
> The series is based on Ignacio Encinas's v3 from March 2024 [1].
> Ignacio dropped the series and agreed to let me give it a try,
> so I am sending it as a new series.
> The "hostname:" patch retains his work and credits him with
> Based-on-patch-by.
>
> Changes since Ignacio's v3:
> [...]
Thanks for thoroughly collecting and including all of the review
feedback from the earlier round. I gave the series only a fairly cursory
read, but I didn't see anything to complain about.
-Peff
^ permalink raw reply [flat|nested] 15+ messages in thread