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the-art-of-command-line
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Merge 5f8a35f225 into ce2e0471da

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Dwaraka Nath 2015-08-15 21:50:11 +00:00
parent ce2e0471da 5f8a35f225
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@ -118,7 +118,7 @@ Notes:
- In Bash, note there are lots of kinds of variable expansion. Checking a variable exists: `${name:?error message}`. For example, if a Bash script requires a single argument, just write `input_file=${1:?usage: $0 input_file}`. Arithmetic expansion: `i=$(( (i + 1) % 5 ))`. Sequences: `{1..10}`. Trimming of strings: `${var%suffix}` and `${var#prefix}`. For example if `var=foo.pdf`, then `echo ${var%.pdf}.txt` prints `foo.txt`. - In Bash, note there are lots of kinds of variable expansion. Checking a variable exists: `${name:?error message}`. For example, if a Bash script requires a single argument, just write `input_file=${1:?usage: $0 input_file}`. Arithmetic expansion: `i=$(( (i + 1) % 5 ))`. Sequences: `{1..10}`. Trimming of strings: `${var%suffix}` and `${var#prefix}`. For example if `var=foo.pdf`, then `echo ${var%.pdf}.txt` prints `foo.txt`.
- Brace expansion using `{`...`}` can reduce having to re-type similar text and automate combinations of items. This is helpful in examples like `mv foo.{txt,pdf} some-dir` (which moves both files), `cp somefile{,.bak}` (which expands to - Brace expansion using `{`...`}` can reduce having to re-type similar text and automate combinations of items. This is helpful in examples like `mv foo.{txt,pdf} some-dir` (which moves both files), `cp somefile{,.bak}` (which expands to
`cp somefile somefile.bak`) or `mkdir -p test-{a,b,c}/subtest-{1,2,3}` (which expands all possible combinations and creates a directory tree). `cp somefile somefile.bak`) or `mkdir -p test-{a,b,c}/subtest-{1,2,3}` (which expands all possible combinations and creates a directory tree).
- The output of a command can be treated like a file via `<(some command)`. For example, compare local `/etc/hosts` with a remote one: - The output of a command can be treated like a file via `<(some command)`. For example, compare local `/etc/hosts` with a remote one:
@ -161,6 +161,10 @@ Notes:
- For a simple web server for all files in the current directory (and subdirs), available to anyone on your network, use: - For a simple web server for all files in the current directory (and subdirs), available to anyone on your network, use:
`python -m SimpleHTTPServer 7777` (for port 7777 and Python 2) and `python -m http.server 7777` (for port 7777 and Python 3). `python -m SimpleHTTPServer 7777` (for port 7777 and Python 2) and `python -m http.server 7777` (for port 7777 and Python 3).
- Likewise, for a simple php web server to serve all the files in the current directory, use `php -S localhost:7777`. To expose it to people in your network, `php -S 0.0.0.0:7777`
- To expose the `jekyll` content in your folder, use `jekyll serve` and to expose the same to all users in the network, `jekyll serve --host 0.0.0.0`
- For running a command with privileges, use `sudo` (for root) or `sudo -u` (for another user). Use `su` or `sudo bash` to actually run a shell as that user. Use `su -` to simulate a fresh login as root or another user. - For running a command with privileges, use `sudo` (for root) or `sudo -u` (for another user). Use `su` or `sudo bash` to actually run a shell as that user. Use `su -` to simulate a fresh login as root or another user.