cat(1)cat(1)NAMEcat - Concatenates or displays files
SYNOPSIScat [-benrstuv] file... | -
The cat command reads each specified file in sequence and writes it to
standard output.
STANDARDS
Interfaces documented on this reference page conform to industry stan‐
dards as follows:
cat: XCU5.0
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
OPTIONS
[Tru64 UNIX] Omits line numbers from blank lines when -n is specified.
If you specify the -b option, the -n option is automatically invoked
with it. [Tru64 UNIX] Same as the -v option with a $ (dollar sign)
character displayed at the end of each line. [Tru64 UNIX] Displays
output lines preceded by line numbers, numbered sequentially from 1.
[Tru64 UNIX] Replaces multiple consecutive empty lines with one empty
line, so that there is never more than one empty line between lines
containing characters. [Tru64 UNIX] Does not display a message if cat
cannot find an input file. (Silent option.) [Tru64 UNIX] Same as the
-v option, with the tab character printed as <Ctrl-i> (^I). Does not
buffer output. Writes bytes from the input file to standard output
without delay as each is read. [Tru64 UNIX] Displays nonprinting
characters so that they are visible.
OPERANDS
The name of the file to be displayed.
If you do not specify a file or if you specify - (dash) instead
of file, cat reads from standard input. The cat command accepts
multiple occurrences of - (dash) as a file argument.
DESCRIPTION
[Tru64 UNIX] The cat command is frequently used with > (redirection
symbol) to concatenate the specified files and write them to the speci‐
fied destination. (See CAUTIONS.) The cat command is also used with >>
to append a file to another file.
CAUTIONS
Do not redirect output to one of the input files using the > (redirect‐
ion symbol). If you do this, you lose the original data in the input
file because the shell truncates it before cat can read it. (See also
the sh command.)
EXIT STATUS
The following exit values are returned: Successful completion. An
error occurred.
EXAMPLES
To display the file notes, enter: cat notes
If the file is longer than one screenful, it scrolls by too
quickly to read. To display a file one page at a time, use the
more command. To concatenate several files, enter: cat sec‐
tion1.1 section1.2 section1.3 > section1
This creates a file named section1 that is a copy of section1.1
followed by section1.2 and section1.3. To suppress error mes‐
sages about files that do not exist, enter: cat-s section2.1
section2.2 section2.3 > section2
If section2.1 does not exist, this command concatenates sec‐
tion2.2 and section2.3. Note that the message goes to standard
error, so it does not appear in the output file. The result is
the same if you do not use the -s option, except that cat dis‐
plays the error message: cat: cannot open section2.1
You may want to suppress this message with the -s option when
you use the cat command in shell procedures. To append one file
to the end of another, enter: cat section1.4 >> section1
The >> in this command specifies that a copy of section1.4 be
added to the end of section1. If you want to replace the file,
use a single > symbol. To add text to the end of a file, enter:
cat >> notes Get milk on the way home <Ctrl-d>
Get milk on the way home is added to the end of notes. With
this syntax, the cat command does not display a prompt; it waits
for you to enter text. Press the End-of-File key sequence
(<Ctrl-d> above) to indicate you are finished. To concatenate
several files with text entered from the keyboard, enter: cat
section3.1 - section3.3 > section3
This concatenates section3.1, text from the keyboard, and sec‐
tion3.3 to create the file section3. To concatenate several
files with output from another command, enter: ls | cat sec‐
tion4.1 - > section4
This copies section4.1, and then the output of the ls command to
the file section4. To get two pieces of input from the terminal
(when standard input is a terminal) with a single command invo‐
cation, enter: cat start - middle - end > file1
If standard input is a regular file, however, the preceding com‐
mand is equivalent to the following: cat start - middle
/dev/null end > file1
This is because the entire contents of the file would be con‐
sumed by cat the first time it saw - (dash) as a file argument.
An End-of-File condition would then be detected immediately when
- (dash) appeared the second time.
ENVIRONMENT VARIABLES
The following environment variables affect the execution of cat: Pro‐
vides a default value for the internationalization variables that are
unset or null. If LANG is unset or null, the corresponding value from
the default locale is used. If any of the internationalization vari‐
ables contain an invalid setting, the utility behaves as if none of the
variables had been defined. If set to a non-empty string value, over‐
rides the values of all the other internationalization variables.
Determines the locale for the interpretation of sequences of bytes of
text data as characters (for example, single-byte as opposed to multi‐
byte characters in arguments). Determines the locale for the format
and contents of diagnostic messages written to standard error. Deter‐
mines the location of message catalogues for the processing of LC_MES‐
SAGES.
SEE ALSO
Commands: more(1), ksh(1), pack(1), pg(1), pr(1), Bourne shell sh(1b),
POSIX shell sh(1p)
Standards: standards(5)cat(1)