Commit 3baed193 authored by Zbigniew Jędrzejewski-Szmek's avatar Zbigniew Jędrzejewski-Szmek
Browse files

Simplify the meaning of %s

The rules governing %s where just too complicated. First of
all, looking at $SHELL is dangerous. For systemd --system,
it usually wouldn't be set. But it could be set if the admin
first started a debug shell, let's say /sbin/sash, and then
launched systemd from it. This shouldn't influence how daemons
are started later on, so is better ignored. Similar reasoning
holds for session mode. Some shells set $SHELL, while other
set it only when it wasn't set previously (e.g. zsh). This
results in fragility that is better avoided by ignoring $SHELL

With $SHELL out of the way, simplify things by saying that
%s==/bin/sh for root, and the configured shell otherwise.
get_shell() is the only caller, so it can be inlined.

Fixes one issue seen with 'make check'.
parent a63a5c46
......@@ -1270,7 +1270,14 @@
<entry>User shell</entry>
<entry>This is the shell of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
<entry>This is the shell of the configured
user of the unit, or (if none is set) the user
running the systemd instance. If the user is
<literal>root</literal> (UID equal to 0), the
shell configured in account database is
ignored and <filename>/bin/sh</filename> is
always used.
......@@ -190,28 +190,37 @@ static char *specifier_user_shell(char specifier, void *data, void *userdata) {
ExecContext *c;
int r;
const char *username, *shell;
char *ret;
c = unit_get_exec_context(u);
/* return HOME if set, otherwise from passwd */
if (!c || !c->user) {
char *sh;
if (c && c->user)
username = c->user;
username = "root";
r = get_shell(&sh);
if (r < 0)
return strdup("/bin/sh");
/* return /bin/sh for root, otherwise the value from passwd */
r = get_user_creds(&username, NULL, NULL, NULL, &shell);
if (r < 0) {
"Failed to determine shell: %s",
return NULL;
return sh;
if (!path_is_absolute(shell)) {
"Shell %s is not absolute, ignoring.",
username = c->user;
r = get_user_creds(&username, NULL, NULL, NULL, &shell);
if (r < 0)
return strdup("/bin/sh");
ret = strdup(shell);
if (!ret)
return strdup(shell);
return ret;
char *unit_name_printf(Unit *u, const char* format) {
......@@ -5246,53 +5246,6 @@ int get_home_dir(char **_h) {
return 0;
int get_shell(char **_sh) {
char *sh;
const char *e;
uid_t u;
struct passwd *p;
/* Take the user specified one */
e = getenv("SHELL");
if (e) {
sh = strdup(e);
if (!sh)
return -ENOMEM;
*_sh = sh;
return 0;
/* Hardcode home directory for root to avoid NSS */
u = getuid();
if (u == 0) {
sh = strdup("/bin/sh");
if (!sh)
return -ENOMEM;
*_sh = sh;
return 0;
/* Check the database... */
errno = 0;
p = getpwuid(u);
if (!p)
return errno ? -errno : -ESRCH;
if (!path_is_absolute(p->pw_shell))
return -EINVAL;
sh = strdup(p->pw_shell);
if (!sh)
return -ENOMEM;
*_sh = sh;
return 0;
void fclosep(FILE **f) {
if (*f)
......@@ -519,7 +519,6 @@ bool in_initrd(void);
void warn_melody(void);
int get_shell(char **ret);
int get_home_dir(char **ret);
static inline void freep(void *p) {
......@@ -164,7 +164,7 @@ static void test_unit_printf(void) {
expect(u, "%u", root->pw_name);
expect(u, "%U", root_uid);
expect(u, "%h", root->pw_dir);
expect(u, "%s", root->pw_shell);
expect(u, "%s", "/bin/sh");
expect(u, "%m", mid);
expect(u, "%b", bid);
expect(u, "%H", host);
......@@ -184,7 +184,7 @@ static void test_unit_printf(void) {
expect(u2, "%u", root->pw_name);
expect(u2, "%U", root_uid);
expect(u2, "%h", root->pw_dir);
expect(u2, "%s", root->pw_shell);
expect(u2, "%s", "/bin/sh");
expect(u2, "%m", mid);
expect(u2, "%b", bid);
expect(u2, "%H", host);
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