Concatenate and print files (POSIX)
Syntax:
cat [-cuw] [-n|-r] [file...]
Options:
- -c
- Compress sequences of multiple newline characters into single newlines.
- -n
- Print line numbers, but don't restart the number for each new file.
- -r
- Print line numbers, restarting the number for each new file.
- -u
- Write unbuffered output.
Data from the input file(s) is written to the standard output without delay as each file is read.
- -w
- Wait at the end of a line for 100 ms for each occurrence of -w.
- file
- The pathname of an input file.
If no files are specified, standard input is used.
If a file is the dash character (-),
cat reads from standard input at that point in the sequence.
Description:
The cat utility reads files in the order you specify
and writes their contents to standard output.
Examples:
Write the contents of myfile to standard output:
cat myfile
Concatenate doc1 and doc2
and write the result to doc.all:
cat doc1 doc2 > doc.all
Exit status:
- 0
- All input files were output successfully.
- >0
- An error occurred.
Caveats:
Because of the shell language mechanism used to perform output redirection, a command such as:
cat doc doc.end > doc
causes the original data in doc to be lost.
The file doc is opened for write by the shell, and therefore
truncated to zero length, before cat is executed.