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authorEtan Reisner <deryni@unreliablesource.net>2015-04-29 22:11:20 -0400
committerEtan Reisner <deryni@unreliablesource.net>2015-05-07 21:07:35 -0400
commit8b7a2fff9a71b8fa8754947434b8b1f184ed2de1 (patch)
tree91f766983c3237e9b5228280dce3bc3521dc9cce /bash.html.markdown
parent54b38b293ff7e45b3e131571f30200cc935fce02 (diff)
Don't use ALL_CAPS variable names.
ALL_CAPS variable names are traditionally "reserved" for use by the shell/system. (People often try to use PATH for things locally and then wonder why their commands all stop working for example.
Diffstat (limited to 'bash.html.markdown')
-rw-r--r--bash.html.markdown58
1 files changed, 29 insertions, 29 deletions
diff --git a/bash.html.markdown b/bash.html.markdown
index 4c50c653..937d2c96 100644
--- a/bash.html.markdown
+++ b/bash.html.markdown
@@ -32,40 +32,40 @@ echo Hello world!
echo 'This is the first line'; echo 'This is the second line'
# Declaring a variable looks like this:
-VARIABLE="Some string"
+Variable="Some string"
# But not like this:
-VARIABLE = "Some string"
-# Bash will decide that VARIABLE is a command it must execute and give an error
+Variable = "Some string"
+# Bash will decide that Variable is a command it must execute and give an error
# because it can't be found.
# Or like this:
-VARIABLE= 'Some string'
+Variable= 'Some string'
# Bash will decide that 'Some string' is a command it must execute and give an
-# error because it can't be found. (In this case the 'VARIABLE=' part is seen
+# error because it can't be found. (In this case the 'Variable=' part is seen
# as a variable assignment valid only for the scope of the 'Some string'
# command.)
# Using the variable:
-echo $VARIABLE
-echo "$VARIABLE"
-echo '$VARIABLE'
+echo $Variable
+echo "$Variable"
+echo '$Variable'
# When you use the variable itself — assign it, export it, or else — you write
# its name without $. If you want to use variable's value, you should use $.
# Note that ' (single quote) won't expand the variables!
# String substitution in variables
-echo ${VARIABLE/Some/A}
+echo ${Variable/Some/A}
# This will substitute the first occurance of "Some" with "A"
# Substring from a variable
-LENGTH=7
-echo ${VARIABLE:0:LENGTH}
+Length=7
+echo ${Variable:0:Length}
# This will return only the first 7 characters of the value
# Default value for variable
-echo ${FOO:-"DefaultValueIfFOOIsMissingOrEmpty"}
-# This works for null (FOO=) and empty string (FOO=""); zero (FOO=0) returns 0.
+echo ${Foo:-"DefaultValueIfFooIsMissingOrEmpty"}
+# This works for null (Foo=) and empty string (Foo=""); zero (Foo=0) returns 0.
# Note that it only returns default value and doesn't change variable value.
# Builtin variables:
@@ -78,12 +78,12 @@ echo "Scripts arguments seperated in different variables: $1 $2..."
# Reading a value from input:
echo "What's your name?"
-read NAME # Note that we didn't need to declare a new variable
-echo Hello, $NAME!
+read Name # Note that we didn't need to declare a new variable
+echo Hello, $Name!
# We have the usual if structure:
# use 'man test' for more info about conditionals
-if [ $NAME -ne $USER ]
+if [ $Name -ne $USER ]
then
echo "Your name isn't your username"
else
@@ -95,14 +95,14 @@ echo "Always executed" || echo "Only executed if first command fails"
echo "Always executed" && echo "Only executed if first command does NOT fail"
# To use && and || with if statements, you need multiple pairs of square brackets:
-if [ $NAME == "Steve" ] && [ $AGE -eq 15 ]
+if [ $Name == "Steve" ] && [ $Age -eq 15 ]
then
- echo "This will run if $NAME is Steve AND $AGE is 15."
+ echo "This will run if $Name is Steve AND $Age is 15."
fi
-if [ $NAME == "Daniya" ] || [ $NAME == "Zach" ]
+if [ $Name == "Daniya" ] || [ $Name == "Zach" ]
then
- echo "This will run if $NAME is Daniya OR Zach."
+ echo "This will run if $Name is Daniya OR Zach."
fi
# Expressions are denoted with the following format:
@@ -171,7 +171,7 @@ echo "There are $(ls | wc -l) items here."
echo "There are `ls | wc -l` items here."
# Bash uses a case statement that works similarly to switch in Java and C++:
-case "$VARIABLE" in
+case "$Variable" in
#List patterns for the conditions you want to meet
0) echo "There is a zero.";;
1) echo "There is a one.";;
@@ -179,10 +179,10 @@ case "$VARIABLE" in
esac
# for loops iterate for as many arguments given:
-# The contents of $VARIABLE is printed three times.
-for VARIABLE in {1..3}
+# The contents of $Variable is printed three times.
+for Variable in {1..3}
do
- echo "$VARIABLE"
+ echo "$Variable"
done
# Or write it the "traditional for loop" way:
@@ -193,16 +193,16 @@ done
# They can also be used to act on files..
# This will run the command 'cat' on file1 and file2
-for VARIABLE in file1 file2
+for Variable in file1 file2
do
- cat "$VARIABLE"
+ cat "$Variable"
done
# ..or the output from a command
# This will cat the output from ls.
-for OUTPUT in $(ls)
+for Output in $(ls)
do
- cat "$OUTPUT"
+ cat "$Output"
done
# while loop:
@@ -230,7 +230,7 @@ bar ()
}
# Calling your function
-foo "My name is" $NAME
+foo "My name is" $Name
# There are a lot of useful commands you should learn:
# prints last 10 lines of file.txt