CAT(1) User Commands CAT(1)


NAME


cat - concatenate and display files

SYNOPSIS


/usr/bin/cat
/usr/bin/cat [-nbsuvet] [file...]


ksh93
cat [-bdenstuvABDEST] [file...]


DESCRIPTION


/usr/bin/cat
The cat utility reads each file in sequence and writes it on the standard
output. Thus:

example% cat file


prints file on your terminal, and:

example% cat file1 file2 >file3


concatenates file1 and file2, and writes the results in file3. If no
input file is given, cat reads from the standard input file.

ksh93
The cat built-in in ksh93 is associated with the /bin and /usr/bin paths.
It is invoked when cat is executed without a pathname prefix and the
pathname search finds a /bin/cat or /usr/bin/cat executable. cat copies
each file in sequence to the standard output. If no file is specified, or
if the file is -, cat copies from standard input starting at the current
location.

OPTIONS


/usr/bin/cat
The following options are supported by /usr/bin/cat:

-b
Number the lines, as -n, but omit the line numbers from blank
lines.


-n
Precede each line output with its line number.


-s
cat is silent about non-existent files.


-u
The output is not buffered.

Buffered output is the default.


-v
Non-printing characters, with the exception of tabs, NEWLINEs and
form feeds, are printed visibly. ASCII control characters (octal
000 - 037) are printed as ^n, where n is the corresponding ASCII
character in the range octal 100 - 137 (@, A, B, C, ..., X, Y, Z,
[, \, ], ^, and _); the DEL character (octal 0177) is printed ^?.
Other non-printable characters are printed as M-x, where x is the
ASCII character specified by the low-order seven bits.


When used with the -v option, the following options can be used:

-e
A $ character is printed at the end of each line, prior to the
NEWLINE.


-t
Tabs are printed as ^Is and form feeds to be printed as ^Ls.


The -e and -t options are ignored if the -v option is not specified.

ksh93
ksh93 cat supports the following options:

-b --number-nonblank
Number lines as with -n but omit line numbers
from blank lines.


-d --dos-input
Open input files in text mode. Removes RETURNs
in front of NEWLINEs on some systems.


-e
Equivalent to -vE.


-n --number
Insert a line number at the beginning of each
line.


-s
Equivalent to -S for att universe and -B
otherwise.


-t
Equivalent to -vT.


-u --unbuffer
Do not delay the output by buffering.


-v --show-nonprinting
Cause non-printing characters (with the
exception of TABs, NEWLINEs, and form feeds) to
be output as printable character sequences.
ASCII control characters are printed as ^n,
where n is the corresponding ASCII character in
the range octal 100-137. The DEL character
(octal 0177) is copied as ^?. Other non-
printable characters are copied as M-x where x
is the ASCII character specified by the low-
order seven bits. Multi-byte characters in the
current locale are treated as printable
characters.


-A --show-all
Equivalent to -vET.


-B --squeeze-blank
Replace multiple adjacent NEWLINE characters
with one NEWLINE.


-D --dos-output
Open output files in text mode. Insert RETURNs
in front of NEWLINEs on some systems.


-E --show-ends
Insert a $ before each NEWLINE.


-S --silent
cat is silent about non-existent files.


-T --show-blank
Copies TABs as ^I and form feeds as ^L.


OPERANDS


The following operand is supported:

file
A path name of an input file. If no file is specified, the
standard input is used. If file is -, cat reads from the standard
input at that point in the sequence. cat does not close and
reopen standard input when it is referenced in this way, but
accepts multiple occurrences of - as file.


USAGE


See largefile(5) for the description of the behavior of cat when
encountering files greater than or equal to 2 Gbyte ( 2^31 bytes).

EXAMPLES


Example 1: Concatenating a File




The following command writes the contents of the file myfile to standard
output:


example% cat myfile


Example 2: Concatenating Two files into One




The following command concatenates the files doc1 and doc2 and writes the
result to doc.all.


example% cat doc1 doc2 > doc.all


Example 3: Concatenating Two Arbitrary Pieces of Input with a Single


Invocation


When standard input is a terminal, the following command gets two
arbitrary pieces of input from the terminal with a single invocation of
cat:


example% cat start - middle - end > file


when standard input is a terminal, gets two arbitrary pieces of input
from the terminal with a single invocation of cat.


If standard input is a regular file,


example% cat start - middle - end > file


would be equivalent to the following command:


cat start - middle /dev/null end > file


because the entire contents of the file would be consumed by cat the
first time - was used as a file operand and an end-of-file condition
would be detected immediately when -was referenced the second time.


ENVIRONMENT VARIABLES


See environ(5) for descriptions of the following environment variables
that affect the execution of cat: LANG, LC_ALL, LC_CTYPE, LC_MESSAGES,
and NLSPATH.

EXIT STATUS


The following exit values are returned:

0
All input files were output successfully.


>0
An error occurred.


ATTRIBUTES


See attributes(5) for descriptions of the following attributes:

/usr/bin/cat

+--------------------+-------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-------------------+
|CSI | Enabled |
+--------------------+-------------------+
|Interface Stability | Committed |
+--------------------+-------------------+
|Standard | See standards(5). |
+--------------------+-------------------+

ksh93

+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | See below. |
+--------------------+-----------------+


The ksh93 built-in binding to /bin and /usr/bin is Volatile. The built-
in interfaces are Uncommitted.

SEE ALSO


touch(1), attributes(5), environ(5), largefile(5), standards(5)

NOTES


Redirecting the output of cat onto one of the files being read causes the
loss of the data originally in the file being read. For example,

example% cat filename1 filename2 > filename1


causes the original data in filename1 to be lost.


April 8, 2008 CAT(1)