来自Bash的Perl / Python / Ruby运行行

Question

I want to run a Ruby/Python one-liner in a shell script, like:

python 'print "hello world"'

or

ruby 'puts "hello world"'

or something like that so I can quickly pipe the input elsewhere.

Answer 1

Since version 2.05b, bash can redirect standard input (stdin) from a "here string" using the <<< operator.

$ python <<< 'print "hello world"'
hello world
$ ruby <<< 'puts "hello world"'
hello world

Answer 2

Each of these commands has a switch to execute a string passed as an argument. For python, it's -c :

$ python -c 'print "hello world"'
hello world

For ruby, it's -e :

$ ruby -e 'puts "hello world"'
hello world

By the way, the output of python --help , ruby --help or looking in the man page for either program would give you the answer.

Answer 3

使用解释器的参数，告诉它下一个参数是要运行的代码。

python -c 'print "hello world"'

Answer 4

对于Ruby：

ruby -e 'puts "Hello world"'

Answer 5

If you mean using a one liner of perl/awk/python in a pipe, it is just like most other Unix utilities:

$ python -c 'print "hello"' | tr "[a-z]" "[A-Z]"
HELLO
$ ruby -e 'puts "hello"' | tr "[a-z]" "[A-Z]"
HELLO
$ python -c 'print "GREETINGS"'  | perl -lpe 's/([EI])/lc($1)/ge'
GReeTiNGS

Answer 6

In Perl, from command line:

perl -e 'print "Hello World\n";'

Or inside bash script:

#!/bin/bash

perl -e 'print "Hello World\n";'

Answer 7

You need neither Perl, Python or Ruby to pipe a fixed string to another application. The echo program can be used for that.

$ echo 'foo' | cat
foo

See explainshell.com for more infos.