diff options
| -rw-r--r-- | bash.html.markdown | 45 | ||||
| -rw-r--r-- | c.html.markdown | 2 | ||||
| -rw-r--r-- | r.html.markdown | 11 | ||||
| -rw-r--r-- | tmux.html.markdown | 3 |
4 files changed, 47 insertions, 14 deletions
diff --git a/bash.html.markdown b/bash.html.markdown index 81d586c4..3b163638 100644 --- a/bash.html.markdown +++ b/bash.html.markdown @@ -111,12 +111,45 @@ ls -l # Lists every file and directory on a separate line # .txt files in the current directory: ls -l | grep "\.txt" -# You can also redirect a command, input and error output. -python2 hello.py < "input.in" -python2 hello.py > "output.out" -python2 hello.py 2> "error.err" -# The output error will overwrite the file if it exists, if you want to -# concatenate them, use ">>" instead. +# You can redirect command input and output (stdin, stdout, and stderr). +# Read from stdin until ^EOF$ and overwrite hello.py with the lines +# between "EOF": +cat > hello.py << EOF +#!/usr/bin/env python +from __future__ import print_function +import sys +print("#stdout", file=sys.stdout) +print("#stderr", file=sys.stderr) +for line in sys.stdin: + print(line, file=sys.stdout) +EOF + +# Run hello.py with various stdin, stdout, and stderr redirections: +python hello.py < "input.in" +python hello.py > "output.out" +python hello.py 2> "error.err" +python hello.py > "output-and-error.log" 2>&1 +python hello.py > /dev/null 2>&1 +# The output error will overwrite the file if it exists, +# if you want to append instead, use ">>": +python hello.py >> "output.out" 2>> "error.err" + +# Overwrite output.txt, append to error.err, and count lines: +info bash 'Basic Shell Features' 'Redirections' > output.out 2>> error.err +wc -l output.out error.err + +# Run a command and print its file descriptor (e.g. /dev/fd/123) +# see: man fd +echo <(echo "#helloworld") + +# Overwrite output.txt with "#helloworld": +cat > output.out <(echo "#helloworld") +echo "#helloworld" > output.out +echo "#helloworld" | cat > output.out +echo "#helloworld" | tee output.out >/dev/null + +# Cleanup temporary files verbosely (add '-i' for interactive) +rm -v output.out error.err output-and-error.log # Commands can be substituted within other commands using $( ): # The following command displays the number of files and directories in the diff --git a/c.html.markdown b/c.html.markdown index 6daabe94..874197d3 100644 --- a/c.html.markdown +++ b/c.html.markdown @@ -84,7 +84,7 @@ int main() { // doubles are usually 64-bit floating-point numbers double x_double = 0.0; // real numbers without any suffix are doubles - // Integral types may be unsigned. + // integer types may be unsigned (only positive) unsigned short ux_short; unsigned int ux_int; unsigned long long ux_long_long; diff --git a/r.html.markdown b/r.html.markdown index 7cb56fd7..c555d748 100644 --- a/r.html.markdown +++ b/r.html.markdown @@ -179,7 +179,7 @@ c(3,3,3,2,2,1) # 3 3 3 2 2 1 # You can also have infinitely large or small numbers class(Inf) # "numeric" class(-Inf) # "numeric" -# You might use "Inf", for example, in integrate( dnorm(x), 3, Inf); +# You might use "Inf", for example, in integrate(dnorm, 3, Inf); # this obviates Z-score tables. # BASIC ARITHMETIC @@ -236,11 +236,12 @@ c('Z', 'o', 'r', 'r', 'o') == "Z" # TRUE FALSE FALSE FALSE FALSE # FACTORS # The factor class is for categorical data # Factors can be ordered (like childrens' grade levels) or unordered (like gender) -factor(c("female", "female", "male", "NA", "female")) -# female female male NA female -# Levels: female male NA +factor(c("female", "female", "male", NA, "female")) +# female female male <NA> female +# Levels: female male # The "levels" are the values the categorical data can take -levels(factor(c("male", "male", "female", "NA", "female"))) # "female" "male" "NA" +# Note that missing data does not enter the levels +levels(factor(c("male", "male", "female", NA, "female"))) # "female" "male" # If a factor vector has length 1, its levels will have length 1, too length(factor("male")) # 1 length(levels(factor("male"))) # 1 diff --git a/tmux.html.markdown b/tmux.html.markdown index de3a8341..9eb96303 100644 --- a/tmux.html.markdown +++ b/tmux.html.markdown @@ -2,8 +2,7 @@ category: tool tool: tmux contributors: - - ["kaernyk", "https://github.com/kaernyk"] - - ["jmaud", "https://github.com/jmaud"] + - ["wzsk", "https://github.com/wzsk"] filename: LearnTmux.txt --- |