tabs(1) — Commands
NAME
tabs − Sets tab stops on terminals
SYNOPSIS
tabs [tab_spec] [+mnumber] [-Tterminal]
The tabs command clears up to 20 previous tabs and sets up to 40 tabs on the terminal according to the supplied tab_spec.
FLAGS
If the same flag occurs more than once, only the last one takes effect.
-nSpecifies repetitive tab stops separated by a uniform number of column positions, n, where n is a single-digit number. The default usage of tabs with no arguments is equivalent to tabs -8. If you use -0, the tab stops are cleared and no new ones are set.
-Tterminal
Identifies the terminal so that tabs can set tabs and margins correctly. The terminal argument is one of the conventional terminal names supported by your system.
If the terminal you specify is not known to the system, tabs tries a general value that works for most terminals.
If you do not provide a -T flag, tabs uses the TERM shell variable.
+mnumber
Moves all tabs to the right number columns, and makes column number+1 the left margin. (Note that columns = bytes.) If m is given without a value, 10 is assumed. The leftmost margin on most terminals is defined by m0.
DESCRIPTION
The tab_spec argument can be a flag representing one of the pre-set tab specifications listed below. It can also be an alternative specification using either column numbers or the name of an existing file, as described below. If you do not specify a tab_spec, the default value is -8.
The available flags cover formats required by most structured programming languages.
When you use the tabs command, always consider the leftmost column number to be 1, even if your terminal refers to it as 0 (zero). Tab-stop position n means that tabbing to position n causes the next character output to be in the n+1th column position on that line.
Tab Specification Flags
-aSets the tabs to 1, 10, 16, 36, and 72.
-a2Sets the tabs to 1, 10, 16, 40, and 72.
-cSets the tabs to 1, 8, 12, 16, 20, and 55 (COBOL normal format)
-c2Sets the tabs to 1, 6, 10, 14, and 49 (COBOL compact format, columns 1 to 6 omitted). With this code, the first column position corresponds to card column 7. One space gets you to column 8, and a tab reaches column 12. Files using this code must include the following format specification:
<:t-c2 m6 s66 d:>
See Format Specifications later in this manpage.
-c3Sets the tabs to 1, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58, 62, and 67 (COBOL compact format with more tabs than -c2). This is the recommended format for COBOL. Files using this code must include the following format specification:
<:t-c3 m6 s66 d:>
-fSets the tabs to 1, 7, 11, 15, 19, and 23 (FORTRAN).
-pSets the tabs to 1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, and 61 (PL/I).
-sSets the tabs to 1, 10, and 55 (SNOBOL).
-uSets the tabs to 1, 12, 20, and 44.
In addition to the preset formats, three other types of tab_specs are available:
-numberSets regularly repeating tabs at every number column. The standard tab setting is -8 and is the setting required for use with the nroff -h flag. Another special case is -0, which implies no tabs at all.
number[,number] ...
Sets tabs at the named column numbers (a list in ascending order, separated by commas). You can specify up to 40 numbers. If any number except the first has a plus sign prefix, the prefixed number is added to the previous number for the next setting. Thus, the tab lists 1,10,20,30 and 1,10,+10,+10 provide the same tab settings.
Format Specifications
A format specification consists of a sequence of arguments separated by blanks and enclosed in brackets and colons: <: :>. Each argument consists of a keyletter and an optional value which immediately follows it. The following arguments can be used:
ttabsSpecifies tab settings. tabs can be: a list of column numbers separated by commas, indicating tab stops at the specified columns; a - (dash) followed by a number n, specifying tabs stops every n columns; or a - (dash) followed by a pre-set tab specification, for example a2 (see DESCRIPTION).
ssizeSpecifies a maximum line size, or length. The size specification must be an integer. (size is checked after tabs have been expanded but before the margin is prepended.)
mmargin
Specifies a number of spaces to be inserted at the beginning of each line. The margin specification must be an integer.
dIndicates that the line containing the format specification is to be deleted from the converted file.
eIndicates that the current format should prevail only until another format specification is encountered in the file.
Default values of t-8 and m0 are assumed if t and m arguments are not included in the specification; if s is not included, line size is not checked. If the first line of a file does not contain a format specification, these defaults are assumed for the entire file.
If a format specification can be disguised as a comment, for example ∗ <:t5,10,15 s75 m5:> ∗, you do not need to include the d keyletter.
EXAMPLES
To set tabs every four spaces, enter:
tabs -4