Can we use grep in if condition in shell script?

Can we use grep in if condition in shell script?

If value equals 1 The grep -ic command tells grep to look for the string and be case i nsensitive, and to c ount the results. This is a simple and fast way of checking whether a string exists within a file and if it does perform some action.

How do you write an if else condition in shell script?

If specified condition is not true in if part then else part will be execute. To use multiple conditions in one if-else block, then elif keyword is used in shell. If expression1 is true then it executes statement 1 and 2, and this process continues. If none of the condition is true then it processes else part.

What will grep return?

What does grep do? The grep command searches a text file based on a series of options and search string and returns the lines of the text file which contain the matching search string. The output can also be manipulated or piped into the console depending on what you need to do with the data.

How do you grep for or condition?

Grep OR Operator

1. Grep OR Using \| If you use the grep command without any option, you need to use \| to separate multiple patterns for the or condition.
2. Grep OR Using -E. grep -E option is for extended regexp.
3. Grep OR Using egrep. egrep is exactly same as ‘grep -E’.
4. Grep OR Using grep -e.

How do I run an if statement in bash?

In order to execute a Bash “if else” statement, you have to use four different keywords : if, then, else and fi :

1. if : represents the condition that you want to check;
2. then : if the previous condition is true, then execute a specific command;
3. else : if the previous condition is false, then execute another command;

What is grep in bash?

The grep command searches the given files for lines containing a match to a given pattern list. In other words, use the grep command to search words or strings in a text files. When it finds a match in a file, it will display those line on screen.

How do I write an if statement in Bash?

The if statement starts with the if keyword followed by the conditional expression and the then keyword. The statement ends with the fi keyword. If the TEST-COMMAND evaluates to True , the STATEMENTS gets executed. If TEST-COMMAND returns False , nothing happens; the STATEMENTS get ignored.

How do you write an if statement in Bash?

The syntax of an bash if statement A short explanation of the example: first we check if the file somefile is readable (“if [ -r somefile ]”). If so, we read it into a variable. If not, we check if it actually exists (“elif [ -f somefile ]”).

Does grep fail if no match?

If there’s no match, that should generally be considered a failure, so a return of 0 would not be appropriate. Indeed, grep returns 0 if it matches, and non-zero if it does not.

Where does bash history get stored?

In Bash, your command history is stored in a file ( . bash_history ) in your home directory.