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Full Discussion: Check existence of a login
Top Forums UNIX for Advanced & Expert Users Check existence of a login Post 302172290 by xavier054 on Monday 3rd of March 2008 09:19:39 AM
Old 03-03-2008
MySQL
Quote:
Originally Posted by fpmurphy
No, in general, a shell does not know whether a particular user exists or not. The operating system may know that information.

As for tilde expansion, here is the relevant section from ksh93 s+.
Thanks, this answers my question. Furthermore I was wrong, and you are right: the shell knows only for users already logged at least once on the system. I could test getpwnam() on a set of PCs running Linux with PAM authentication, it failed for PAM logins of users that never logged on the machine. Same occurred with tidlde expansion.

BTW, I understand that getpwnam() manpage is confusing : it claims that /etc/passwd is parsed. But seen the output of last(1), and the outcome of my test, I understand it is rather /var/run/wtmp...

X.
 

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LEARN ABOUT CENTOS

grub2-file

GRUB-FILE(1)						      General Commands Manual						      GRUB-FILE(1)

NAME

       grub-file -- Check if FILE is of specified type.

SYNOPSIS

       grub-file (--is-i386-xen-pae-domu | --is-x86_64-xen-domu |
		  --is-x86-xen-dom0 | --is-x86-multiboot |
		  --is-x86-multiboot2 | --is-arm-linux | --is-arm64-linux |
		  --is-ia64-linux | --is-mips-linux | --is-mipsel-linux |
		  --is-sparc64-linux | --is-powerpc-linux | --is-x86-linux |
		  --is-x86-linux32 | --is-x86-kfreebsd | --is-i386-kfreebsd |
		  --is-x86_64-kfreebsd | --is-x86-knetbsd |
		  --is-i386-knetbsd | --is-x86_64-knetbsd | --is-i386-efi |
		  --is-x86_64-efi | --is-ia64-efi | --is-arm64-efi |
		  --is-arm-efi | --is-hibernated-hiberfil | --is-x86_64-xnu |
		  --is-i386-xnu | --is-xnu-hibr | --is-x86-bios-bootsector)
		  FILE

DESCRIPTION

       grub-file is used to check if FILE is of a specified type.

OPTIONS

       --is-i386-xen-pae-domu
	      Check if FILE can be booted as i386 PAE Xen unprivileged guest kernel

       --is-x86_64-xen-domu
	      Check if FILE can be booted as x86_64 Xen unprivileged guest kernel

       --is-x86-xen-dom0
	      Check if FILE can be used as Xen x86 privileged guest kernel

       --is-x86-multiboot
	      Check if FILE can be used as x86 multiboot kernel

       --is-x86-multiboot2
	      Check if FILE can be used as x86 multiboot2 kernel

       --is-arm-linux
	      Check if FILE is ARM Linux

       --is-arm64-linux
	      Check if FILE is ARM64 Linux

       --is-ia64-linux
	      Check if FILE is IA64 Linux

       --is-mips-linux
	      Check if FILE is MIPS Linux

       --is-mipsel-linux
	      Check if FILE is MIPSEL Linux

       --is-sparc64-linux
	      Check if FILE is SPARC64 Linux

       --is-powerpc-linux
	      Check if FILE is POWERPC Linux

       --is-x86-linux
	      Check if FILE is x86 Linux

       --is-x86-linux32
	      Check if FILE is x86 Linux supporting 32-bit protocol

       --is-x86-kfreebsd
	      Check if FILE is x86 kFreeBSD

       --is-i386-kfreebsd
	      Check if FILE is i386 kFreeBSD

       --is-x86_64-kfreebsd
	      Check if FILE is x86_64 kFreeBSD

       --is-x86-knetbsd
	      Check if FILE is x86 kNetBSD

       --is-i386-knetbsd
	      Check if FILE is i386 kNetBSD

       --is-x86_64-knetbsd
	      Check if FILE is x86_64 kNetBSD

       --is-i386-efi
	      Check if FILE is i386 EFI file

       --is-x86_64-efi
	      Check if FILE is x86_64 EFI file

       --is-ia64-efi
	      Check if FILE is IA64 EFI file

       --is-arm64-efi
	      Check if FILE is ARM64 EFI file

       --is-arm-efi
	      Check if FILE is ARM EFI file

       --is-hibernated-hiberfil
	      Check if FILE is hiberfil.sys in hibernated state

       --is-x86_64-xnu
	      Check if FILE is x86_64 XNU (Mac OS X kernel)

       --is-i386-xnu
	      Check if FILE is i386 XNU (Mac OS X kernel)

       --is-xnu-hibr
	      Check if FILE is XNU (Mac OS X kernel) hibernated image

       --is-x86-bios-bootsector
	      Check if FILE is BIOS bootsector

SEE ALSO

       info grub

								  Web Feb 26 2014						      GRUB-FILE(1)
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