IEEE P1003.2 Draft 11.2 - September 1991 Copyright (c) 1991 by the Institute of Electrical and Electronics Engineers, Inc. 345 East 47th Street New York, NY 10017, USA All rights reserved as an unpublished work. This is an unapproved and unpublished IEEE Standards Draft, subject to change. The publication, distribution, or copying of this draft, as well as all derivative works based on this draft, is expressly prohibited except as set forth below. Permission is hereby granted for IEEE Standards Committee participants to reproduce this document for purposes of IEEE standardization activities only, and subject to the restrictions contained herein. Permission is hereby also granted for member bodies and technical committees of ISO and IEC to reproduce this document for purposes of developing a national position, subject to the restrictions contained herein. Permission is hereby also granted to the preceding entities to make limited copies of this document in an electronic form only for the stated activities. The following restrictions apply to reproducing or transmitting the document in any form: 1) all copies or portions thereof must identify the document's IEEE project number and draft number, and must be accompanied by this entire notice in a prominent location; 2) no portion of this document may be redistributed in any modified or abridged form without the prior approval of the IEEE Standards Department. Other entities seeking permission to reproduce this document, or any portion thereof, for standardization or other activities, must contact the IEEE Standards Department for the appropriate license. Use of information contained in this unapproved draft is at your own risk. IEEE Standards Department Copyright and Permissions 445 Hoes Lane, P.O. Box 1331 Piscataway, NJ 08855-1331, USA +1 (908) 562-3800 +1 (908) 562-1571 [FAX] P1003.2/D11.2 INFORMATION TECHNOLOGY--POSIX 4.65 true - Return true value 4.65.1 Synopsis true 4.65.2 Description The true utility shall return with exit code zero. 4.65.3 Options None. 4.65.4 Operands None. 4.65.5 External Influences 4.65.5.1 Standard Input None. 4.65.5.2 Input Files None. 4.65.5.3 Environment Variables None. 4.65.5.4 Asynchronous Events Default. Copyright c 1991 IEEE. All rights reserved. This is an unapproved IEEE Standards Draft, subject to change. 770 4 Execution Environment Utilities Part 2: SHELL AND UTILITIES P1003.2/D11.2 4.65.6 External Effects 4.65.6.1 Standard Output None. 4.65.6.2 Standard Error None. 4.65.6.3 Output Files None. 4.65.7 Extended Description None. 4.65.8 Exit Status The true utility always exits with a value of zero. 4.65.9 Consequences of Errors Default. BEGIN_RATIONALE 4.65.10 Rationale. (_T_h_i_s _s_u_b_c_l_a_u_s_e _i_s _n_o_t _a _p_a_r_t _o_f _P_1_0_0_3._2) _E_x_a_m_p_l_e_s_,__U_s_a_g_e The true utility is typically used in shell scripts. The special built- in utility : (see 3.14.2) is sometimes more efficient than true. _H_i_s_t_o_r_y__o_f__D_e_c_i_s_i_o_n_s__M_a_d_e The true utility has been retained in POSIX.2, even though the shell special built-in : provides similar functionality, because true is widely used in existing scripts and is less cryptic to novice human script readers. Copyright c 1991 IEEE. All rights reserved. This is an unapproved IEEE Standards Draft, subject to change. 4.65 true - Return true value 771 P1003.2/D11.2 INFORMATION TECHNOLOGY--POSIX END_RATIONALE 4.66 tty - Return user's terminal name 4.66.1 Synopsis tty _O_b_s_o_l_e_s_c_e_n_t _V_e_r_s_i_o_n: tty -s 4.66.2 Description The tty utility shall write to the standard output the name of the terminal that is open as standard input. The name that is used shall be equivalent to the string that would be returned by the POSIX.1 {8} _t_t_y_n_a_m_e() function. 4.66.3 Options The tty utility shall conform to the utility argument syntax guidelines described in 2.10.2. The following option shall be supported by the implementation: -s (Obsolescent.) Do not write the terminal name. Only the exit status shall be affected by this option. The terminal status shall be determined as if the POSIX.1 {8} _i_s_a_t_t_y() function were used. 4.66.4 Operands None. 4.66.5 External Influences Copyright c 1991 IEEE. All rights reserved. This is an unapproved IEEE Standards Draft, subject to change. 772 4 Execution Environment Utilities