How can I check if a program exists from a Bash script?
How can I check if a program exists from a Bash script?
bash
In the shell, what does ” 2>&1 ” mean?
File descriptor 1 is the standard output (stdout). File descriptor 2 is the standard error (stderr). Here is one way to remember this construct (although it is not entirely accurate): at first, 2>1 may look like a good way to redirect stderr to stdout. However, it will actually be interpreted as “redirect stderr to a … Read more
Echo newline in Bash prints literal \n
You could use printf instead: printf “hello\nworld\n” printf has more consistent behavior than echo. The behavior of echo varies greatly between different versions.
How to concatenate string variables in Bash
foo=”Hello” foo=”${foo} World” echo “${foo}” > Hello World In general to concatenate two variables you can just write them one after another: a=”Hello” b=’World’ c=”${a} ${b}” echo “${c}” > Hello World
How do I tell if a regular file does not exist in Bash?
The test command ([ here) has a “not” logical operator which is the exclamation point (similar to many other languages). Try this: if [ ! -f /tmp/foo.txt ]; then echo “File not found!” fi
How can I check if a directory exists in a Bash shell script?
How can I check if a directory exists in a Bash shell script?
How can I get the source directory of a Bash script from within the script itself?
How can I get the source directory of a Bash script from within the script itself?
Input data to a shell script [closed]
AFAI understand you want to use an array: read -r -a names Example: read -r -a names <<< “John Marry Sanford Saunders” echo “${names[0]}” # John echo “${names[1]}” # Marry echo “${names[2]}” # Sanford echo “${names[3]}” # Saunders
How can I manipulate text in bash? [closed]
With awk: awk ‘BEGIN{FS=”[ ,]”; OFS=”,”} {for (i=2; i<=NF; i++) print $i,$1}’ file Output: foo,ted bar,ted zoo,ted ket,john ben,john See: 8 Powerful Awk Built-in Variables – FS, OFS, RS, ORS, NR, NF, FILENAME, FNR
what exactly env command do? [duplicate]
env sets one or more environment variables and then runs the remaining arguments as a command. It’s not significantly different from the following syntax: x='() { :;}; echo vulnerable’ bash -c “echo this is a test” One thing env can do (although the feature is not used in the above example) is create a clean … Read more