If any operand (except one which follows --) starts with a hyphen the behavior is unspecified. [1]
The following table lists the Commands and Utilities. Unless otherwise specified the command or utility is described in the Single UNIX Specification (SUS). When an interface is not defined in the Single UNIX Specification, then the next prevailing standard is referenced (ie., POSIX, SVID).
The behavior of the interfaces described in this section are specified by the following standards.
| Linux Standard Base [2] |
| ISO/IEC 9945:2003 Portable Operating System(POSIX)and The Single UNIX® Specification(SUS) V3 [3] |
Table 8-1. Commands and Utilities
| [ [3] | ar [2] | at [2] | awk [2] | basename [3] |
| batch [2] | bc [2] | cat [3] | chfn [2] | chgrp [2] |
| chmod [3] | chown [2] | chsh [2] | cksum [3] | cmp [3] |
| col [2] | comm [3] | cp [3] | cpio [2] | crontab [2] |
| csplit [3] | cut [2] | date [3] | dd [3] | df [2] |
| diff [3] | dirname [3] | dmesg [2] | du [2] | echo [2] |
| egrep [2] | env [3] | expand [3] | expr [3] | false [3] |
| fgrep [2] | file [2] | find [2] | fold [3] | fuser [2] |
| gencat [3] | getconf [3] | gettext [2] | grep [2] | groupadd [2] |
| groupdel [2] | groupmod [2] | groups [2] | gunzip [2] | gzip [2] |
| head [3] | hostname [2] | iconv [3] | id [3] | install [2] |
| install_initd [2] | ipcrm [2] | ipcs [2] | join [3] | kill [3] |
| killall [2] | ln [3] | locale [3] | localedef [3] | logname [3] |
| lpr [2] | ls [2] | lsb_release [2] | m4 [2] | make [3] |
| man [3] | md5sum [2] | mkdir [3] | mkfifo [3] | mknod [2] |
| mktemp [2] | more [2] | mount [2] | msgfmt [2] | mv [3] |
| newgrp [2] | nice [3] | nl [3] | nohup [3] | od [2] |
| passwd [2] | paste [3] | patch [2] | pathchk [3] | pidof [2] |
| pr [3] | printf [3] | ps [3] | pwd [3] | remove_initd [2] |
| renice [2] | rm [3] | rmdir [3] | sed [2] | sendmail [2] |
| sh [3] | shutdown [2] | sleep [3] | sort [3] | split [3] |
| strip [3] | stty [3] | su [2] | sync [2] | tail [3] |
| tar [2] | tee [3] | test [3] | time [3] | touch [3] |
| tr [3] | true [3] | tsort [3] | tty [3] | umount [2] |
| uname [3] | unexpand [3] | uniq [3] | useradd [2] | userdel [2] |
| usermod [2] | wc [3] | xargs [2] |
| [1] | Thus, applications should place options before operands, or use --, as needed. This text is needed because GNU option parsing differs from POSIX. For example, ls . -a in GNU ls means to list the current directory, showing all files (that is, "." is an operand and -a is an option). In POSIX, "." and -a are both operands, and the command means to list the current directory, and also the file named -a. Suggesting that applications rely on the setting of the POSIXLY_CORRECT environment variable, or try to set it, seems worse than just asking the applictions to invoke commands in ways which work with either the POSIX or GNU behaviors. |
| [2] | Linux Standard Base |
| [3] | ISO/IEC 9945:2003 Portable Operating System(POSIX)and The Single UNIX® Specification(SUS) V3 |