head (Unix)

head (English for "head") is a program for Unix and Unix-like operating systems to output the first lines of a file. The opposite of headis tail, which shows the last lines of a file.

Working method

The syntax of headmany other command line programs is similar :

head [Schalter] <Dateiname>

Usually prints headthe first 10 lines of a file. The switches can be used to select the type (lines, bytes) and number of output.

Typical application examples

The following example outputs the first 20 lines of <Dateiname>:

head -n 20 <Dateiname>

Outputs the first 15 bytes of all files that begin with foo :

head -c 15 foo*

Exotic examples

Many previous Unix versions didn't have the command, so documentation and books referred to sed :

sed 5q foo

Some Unix systems still use the old syntax. The option is -nnot supported there. The following syntax must be used here to output the first 20 lines or the first 50 bytes.

head -20 <Dateiname>
head -50c <Dateiname>

This syntax is out of date and does not correspond to the POSIX standard 1003.1-2001.

Web links

• head: copy the first part of files -  Open Group Base Specification
• head(1): display first few lines of files -  OpenBSD General Commands Manual
• head(1): print the first part of files -  Debian GNU / Linux executables or shell commands man page