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This article mainly introduces the common usage of Perl command line, which can be used for reference by interested friends. I hope you will gain a lot after reading this article.

Replacement of Perl command line

◆ replaces foo in all C programs with bar, and backs up old files to .bak.

Perl-p-i.bak-e's/\ bfoo\ b/bar/g'*.c

Very powerful functions, especially in large programs to do refactoring. I remember it was only used in UltraEdit. If you don't want to back it up, just write it as perl-p-i-e or simpler perl-pie. Well, pie is a good word.

◆ adds one of the values that appear in each file

Perl-i.bak-pe's/ (\ d +) / 1+$1/ge'file1file2... .

◆ replaces the newline character\ r\ nwith\ n

Perl-pie's/\ r\ n /\ n/g'file

Same as the dos2unix command.

◆ replaces the newline character\ nwith\ r\ n

Perl-pie's/\ n /\ r\ n/g'file

Same as the unix2dos command.

Take out part of the file

Displays fields 0-4 and 6, with the delimiter of the field being a space

Perl-lane'print "@ F [0.4] $F [6]" 'file

Very good and powerful, same as awk'print$1,$2,$3,$4,$5,$7'. The parameter name lane is also easy to remember.

◆ if the field delimiter is not a space but a colon, use perl-F:-lane'print "@ F [0.4]\ n" / etc/passwd

Show the part between START and END

Perl-ne'printif/ ^ start $/.. / ^ end $/ 'file

I'm afraid only sed can do this.

In contrast, the part between START and END is not displayed

Perl-ne'printunless/ ^ start $/.. / ^ end $/ 'file

Display the first 50 lines:

Perl-pe'exitif$. > 50'file

Same command head-n50

Do not display the first 10 lines: perl-ne'printunless1..10'file

Display lines 15 to 17: perl-ne'printif15..17'file

Take the first 80 characters per line: perl-lne'printsubstr ($_, 0pj80) = "" 'file

Discard the first 10 characters per line: perl-lne'printsubstr ($_, 10) = "" 'file

Perl command line search

◆ finds comment string: perl-ne'printif/comment/'duptext

This is the normal grep command.

◆ looks for lines that do not contain comment strings: perl-ne'printunless/comment/'duptext

The reverse grep, or grep-v.

◆ looks for lines that contain comment or apple:

Perl-ne'printif/comment/ | | / apple/'duptext, egrep is about to be used for the same function.

Calculation of Perl command line

Calculate the sum of field 4 and the penultimate field:

Perl-lane'print$F [4] + $F [- 2]'

If you use awk, you have to write it as awk' {ifold NFMUI 1 locus printful5percent I}'.

Sorting and reversal of the Perl command line

Files sorted by line: perl-e'printsort'file

The equivalent of a simple sort command.

◆ files are sorted by paragraph: Perl-00-e'printsort'file

Multiple files are sorted by file contents and the merged files are returned:

Perl-0777-e'printsort'file1file2

◆ files are reversed by line: Perl-e'printreverse'file1

Are there any corresponding orders? There is. But it's quite out of line, tac (the reversal of cat)

Numerical calculation of Perl Command Line

Decimal to hexadecimal:

Perl-ne'printf "x\ n", $_'

From 10 to 8: perl-ne'printf "% o\ n", $_'

Hexadecimal to decimal:

Perl-ne'printhex ($_). "\ n"

8-to-decimal:

Perl-ne'printoct ($_). "\ n"

A simple calculator.

Perl-ne'printeval ($_). "\ n"

Other

Start the interactive perl:

Perl-de1

View the content that contains the path:

Perl-le'printfor@INC'

Remarks

Perl command line parameters related to One-Liner:

-0

(in octal) specifies the record delimiter ($/ variable), which defaults to newline

-00, paragraph mode, that is, a continuous exchange of behavior delimiters

-0777, disable the delimiter, that is, the entire file as a record

-a, automatically separate the mode, separate $_ with a space and save it to @ F. Equivalent to @ F=split. The delimiter can be specified using the-F parameter

-F, specify the delimiter of-a, you can use regular expressions

-e, execute the specified script.

-I replace the file in place and back up the old file with the specified extension. If you do not specify an extension, you will not back up.

-l, automatically chomp the input content and automatically add line breaks to the output content

-n, auto loop, equivalent to while () {script;}

-p, auto loop + automatic output, equivalent to while () {script; print;}

Thank you for reading this article carefully. I hope the article "what are the common uses of the Perl command line" shared by the editor will be helpful to you. At the same time, I also hope you will support us and pay attention to the industry information channel. More related knowledge is waiting for you to learn!

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