---
name: "getaliasent"
section: "3"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/setaliasent"
---

# getaliasent(3)

read an alias entry

Part of [setaliasent(3)](/setaliasent/3.md).

## NAME

setaliasent, endaliasent, getaliasent, getaliasent\_r, getaliasbyname, getaliasbyname\_r - read an alias entry

## LIBRARY

Standard C library (*libc*, *-lc*)

## SYNOPSIS

```
#include <aliases.h>
```

**void setaliasent(void);** **void endaliasent(void);**

**struct aliasent \*getaliasent(void);** **int getaliasent\_r(**size\_t size;                      **struct aliasent \*restrict** *result***,**                      **char** *buffer***\[restrict** *size***\], size\_t** *size***,**                      **struct aliasent \*\*restrict** *res***);**

**struct aliasent \*getaliasbyname(const char \****name***);** **int getaliasbyname\_r(**size\_t size;                      **const char \*restrict** *name***,**                      **struct aliasent \*restrict** *result***,**                      **char** *buffer***\[restrict** *size***\], size\_t** *size***,**                      **struct aliasent \*\*restrict** *res***);**

## DESCRIPTION

One of the databases available with the Name Service Switch (NSS) is the aliases database, that contains mail aliases. (To find out which databases are supported, try *getent --help*.) Six functions are provided to access the aliases database.

The **getaliasent**() function returns a pointer to a structure containing the group information from the aliases database. The first time it is called it returns the first entry; thereafter, it returns successive entries.

The **setaliasent**() function rewinds the file pointer to the beginning of the aliases database.

The **endaliasent**() function closes the aliases database.

**getaliasent\_r**() is the reentrant version of the previous function. The requested structure is stored via the first argument but the programmer needs to fill the other arguments also. Not providing enough space causes the function to fail.

The function **getaliasbyname**() takes the name argument and searches the aliases database. The entry is returned as a pointer to a *struct aliasent*.

**getaliasbyname\_r**() is the reentrant version of the previous function. The requested structure is stored via the second argument but the programmer needs to fill the other arguments also. Not providing enough space causes the function to fail.

The *struct aliasent* is defined in *\<aliases.h\>*:

```
struct aliasent {
    char    *alias_name;             /* alias name */
    size_t   alias_members_len;
    char   **alias_members;          /* alias name list */
    int      alias_local;
};
```

## RETURN VALUE

The functions **getaliasent\_r**() and **getaliasbyname\_r**() return a nonzero value on error.

## FILES

The default alias database is the file */etc/aliases*. This can be changed in the */etc/nsswitch.conf* file.

## ATTRIBUTES

For an explanation of the terms used in this section, see [**attributes**(7)](/attributes/7.md).

| | | |
| --- | --- | --- |
| **Interface** | **Attribute** | **Value** |
| **setaliasent**(), **endaliasent**(), **getaliasent\_r**(), **getaliasbyname\_r**() | Thread safety | MT-Safe locale |
| **getaliasent**(), **getaliasbyname**() | Thread safety | MT-Unsafe |

## STANDARDS

GNU.

## HISTORY

The NeXT system has similar routines:

```
#include <aliasdb.h>
void alias_setent(void);
void alias_endent(void);
alias_ent *alias_getent(void);
alias_ent *alias_getbyname(char *name);
```

## EXAMPLES

The following example compiles with *gcc example.c -o example*. It will dump all names in the alias database.

```
#include <aliases.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
int
main(void)
{
    struct aliasent *al;
    setaliasent();
    for (;;) {
        al = getaliasent();
        if (al == NULL)
            break;
        printf("Name: %s\n", al->alias_name);
    }
    if (errno) {
        perror("reading alias");
        exit(EXIT_FAILURE);
    }
    endaliasent();
    exit(EXIT_SUCCESS);
}
```

## SEE ALSO

[**getgrent**(3)](/getgrent/3.md), [**getpwent**(3)](/getpwent/3.md), [**getspent**(3)](/getspent/3.md), [**aliases**(5)](/aliases/5.md)