Bash programming
04 Oct 2018File header
#!/bin/bash
CLI param
echo $1
echo $2
# cli param1 param2
Check param is (not) empty
if [ -z "$1" ]; then
echo "empty param"
fi
if [ ! -z "$1" ]; then
echo "not empty param"
fi
Bash Equals-Separated (e.g., –option=argument) (without getopt[s]) 1
#!/bin/bash
for i in "$@"
do
case $i in
-e=*|--extension=*)
EXTENSION="${i#*=}"
shift # past argument=value
;;
-s=*|--searchpath=*)
SEARCHPATH="${i#*=}"
shift # past argument=value
;;
-l=*|--lib=*)
LIBPATH="${i#*=}"
shift # past argument=value
;;
--default)
DEFAULT=YES
shift # past argument with no value
;;
*)
# unknown option
;;
esac
done
echo "FILE EXTENSION = ${EXTENSION}"
echo "SEARCH PATH = ${SEARCHPATH}"
echo "LIBRARY PATH = ${LIBPATH}"
echo "DEFAULT = ${DEFAULT}"
Varable
Put value to dynamiclly varable
A_VAR='a'
eval "$1_VAR"='cc'
echo $A_VAR
reference a file for variables 2
source FILE
# or
. FILE
Path
Source path
Dirname
$(dirname "$0")
Source path
SOURCE="${BASH_SOURCE[0]}"
echo $SOURCE
Source directory path 3
DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
Execution directory
echo $(pwd)
File and directory
Getting the contents of a directory using shell script. 4
for entry in "$search_dir"/*
do
echo "$entry"
done
Check directory
if [ -d "$DIR" ]; then
exit 0
else
exit 1
fi
Conditionals 5
| Bash Operator | Operator | Description |
|---|---|---|
-eq |
== |
Equal |
-ne |
!= |
Not equal |
-gt |
> |
Greater than |
-ge |
>= |
Greater than or equal |
-lt |
< |
Less than |
-le |
<= |
Less than or equal |
-z |
== |
null Is null |
Looping 6
#!/bin/bash
FILES=/Users/tania/dev/*
for file in $FILES
do
echo $(basename $file)
done
Color
You can use these ANSI escape codes:7
# .---------- constant part!
# vvvv vvvv-- the code from above
RED='\033[0;31m'
NC='\033[0m' # No Color
printf "I ${RED}love${NC} Stack Overflow\n"
#!/bin/bash
RED='\033[0;31m'
YELLO='\033[1;33m'
GREEN='\033[0;32m'
NC='\033[0m' # No Color
echo -e "I ${RED}love${NC} coding"
echo -e "I ${YELLO}love${NC} coding"
echo -e "I ${GREEN}love${NC} coding"
| Color | Code | Color | Code |
|---|---|---|---|
| Black | 0;30m |
Dark Gray | 1;30m |
| Red | 0;31m |
Light Red | 1;31m |
| Green | 0;32m |
Light Green | 1;32m |
| Brown/Orange | 0;33m |
Yellow | 1;33m |
| Blue | 0;34m |
Light Blue | 1;34m |
| Purple | 0;35m |
Light Purple | 1;35m |
| Cyan | 0;36m |
Light Cyan | 1;36m |
| Light Gray | 0;37m |
White | 1;37m |
functions
function get_string()
{
echo "string"
}
STRING=$(get_string)
Pass params into function 8
function get_string()
{
echo "$1"
}
STRING=$(get_string aaa)
echo $STRING