diff options
Diffstat (limited to 'bash.html.markdown')
| -rw-r--r-- | bash.html.markdown | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/bash.html.markdown b/bash.html.markdown index 3f3e49eb..cda877ad 100644 --- a/bash.html.markdown +++ b/bash.html.markdown @@ -25,7 +25,7 @@ Nearly all examples below can be a part of a shell script or executed directly i [Read more here.](http://www.gnu.org/software/bash/manual/bashref.html) ```bash -#!/bin/bash +#!/usr/bin/env bash # First line of the script is shebang which tells the system how to execute # the script: http://en.wikipedia.org/wiki/Shebang_(Unix) # As you already figured, comments start with #. Shebang is also a comment. @@ -74,8 +74,8 @@ echo ${Variable/Some/A} # => A string # Substring from a variable Length=7 -echo ${Variable:0:Length} # => Some st -# This will return only the first 7 characters of the value +echo ${Variable:0:$Length} # => Some st +# This will return 7 characters of the string, starting from the first char # Default value for variable echo ${Foo:-"DefaultValueIfFooIsMissingOrEmpty"} @@ -228,10 +228,13 @@ mv s0urc3.txt dst.txt # sorry, l33t hackers... # Since bash works in the context of a current directory, you might want to # run your command in some other directory. We have cd for changing location: cd ~ # change to home directory +cd # also goes to home directory cd .. # go up one directory # (^^say, from /home/username/Downloads to /home/username) cd /home/username/Documents # change to specified directory cd ~/Documents/.. # still in home directory..isn't it?? +cd - # change to last directory +# => /home/username/Documents # Use subshells to work across directories (echo "First, I'm here: $PWD") && (cd someDir; echo "Then, I'm here: $PWD") @@ -256,6 +259,7 @@ print("#stderr", file=sys.stderr) for line in sys.stdin: print(line, file=sys.stdout) EOF +# Variables will be expanded if the first "EOF" is not quoted # Run the hello.py Python script with various stdin, stdout, and # stderr redirections: |