Some tips for using the Linux awk command-basic commands

The purpose of the tool is to read the text file line-by-row, then slice the read-in text (by default, separated by a space), and then read it to the next line, which is already available. is a format report generation tool that is then used to process text.

Currently, the awk used on linux is gawk(open source awk), abbreviated to Awk.

Usage:

#awk [Options] ' script ' file,file2,... #awk [options] ' PATTERN {action} ' filelist

quoted words, each line from $ Start, $ As the current line, ending with a newline character as the line

commonly used for: awk ' {print$1} ' File

Common options:

- F : Specify field separators awk-f: ' {print '} '/etc/passwd

- V: assigning an initial value to a variable

print function, printing content, with line break

The printf function, which formats the printed content without line breaks, requires the following format:

awk ' {printF ' format ' $} ' file

The format is as follows:

in % begins with a character followed by a

%c Display character ASCII code%d,%i: decimal number%e,%e scientific notation display numerical%g,%g scientific notation format or floating-point format display numeric value%f display floating-point number%u unsigned integer percent display% self%s display string

Modifier

N, such as%10s, the current string occupies 10 cells, not enough to fill empty-: left-aligned, default right-aligned +: Display numeric symbols

Example

Linux1:/home/test #awk ' {printf '%-15s%i\n ", $1,$2} ' 1welcome 0hello 0

Output redirection

Printitems > Output-file

Printitems >> Output-file

Printitems | Command

Special file descriptors

/dev/stdin: Standard input

/dev/stdout Standard Output

/dev/stderr : Error Output

/dev/fd/n a specific file descriptor, such as /dev/stdin is equivalent to /dev/fd/0

For example:

Linux1:/home # awk-f: ' {printf '%-15s%i\n ',$1,$3> '/dev/stderr '} '/etc/passwdroot 0bin 1daemon 2LP 4mail 8games 12wwwrun 30ftp 40nobody 65534

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Some tips for using the Linux awk command-basic commands