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man pages section 1: User Commands

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Updated: Thursday, June 13, 2019
 
 

shift(1)

Name

shift - shell built-in function to traverse either a shell's argument list or a list of field-separated words

Synopsis

sh

shift [n]

csh

shift [variable]

ksh88

*shift [n]

ksh88

+shift [n]

Description

sh

The positional parameters from $n+1 . . . are renamed $1 . . . . If n is not specified, it is assumed to be 1.

csh

The components of argv, or variable, if supplied, are shifted to the left, discarding the first component. It is an error for the variable not to be set or to have a null value.

ksh88

The positional parameters from $n+1 $n+1 . . . are renamed $1 . . ., default n is 1. The parameter n can be any arithmetic expression that evaluates to a non-negative number less than or equal to $#.

On this manual page, ksh88(1) commands that are preceded by one or two * (asterisks) are treated specially in the following ways:

  1. Variable assignment lists preceding the command remain in effect when the command completes.

  2. I/O redirections are processed after variable assignments.

  3. Errors cause a script that contains them to abort.

  4. Words, following a command preceded by ** that are in the format of a variable assignment, are expanded with the same rules as a variable assignment. This means that tilde substitution is performed after the = sign and word splitting and file name generation are not performed.

ksh

shift is a shell special built-in that shifts the positional parameters to the left by the number of places defined by n, or 1 if n is omitted. The number of positional parameters remaining is reduced by the number of places that are shifted.

If n is specified, it is evaluated as an arithmetic expression to determine the number of places to shift. It is an error to shift more than the number of positional parameters or a negative number of places.

The following exit values are returned by shift in ksh:

0

Successful completion. The positional parameters were successfully shifted.

>0

An error occurred.

On this manual page, ksh(1) commands that are preceded by one or two + are treated specially in the following ways:

  1. Variable assignment lists preceding the command remain in effect when the command completes.

  2. I/O redirections are processed after variable assignments.

  3. Errors cause a script that contains them to abort.

  4. They are not valid function names.

  5. Words, following a command preceded by ++ that are in the format of a variable assignment, are expanded with the same rules as a variable assignment. This means that tilde substitution is performed after the = sign and field splitting and file name generation are not performed.

Attributes

See attributes(7) for descriptions of the following attributes:

ATTRIBUTE TYPE
ATTRIBUTE VALUE
Availability
system/core-os

See Also

csh(1), ksh(1), ksh88(1), sh(1), attributes(7)