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When to use printf instead of Echo in Bash?
To avoid this, use printf instead of echo when details matter. echo $var output highly depends on the value of IFS variable. By default it contains space, tab, and newline characters:
What happens when you Echo$ Var in Bash?
This means that when shell is doing field splitting (or word splitting) it uses all these characters as word separators. This is what happens when referencing a variable without double quotes to echo it ( $var) and thus expected output is altered.
How to assign a variable to an alias in Bash?
And eval will only call that alias if also does not start with a number – else eval gets only a null argument. So if both conditions are met eval calls the alias and the variable definition saved in the alias is made, after which the new alias is promptly removed from the hash table.
Can a shell variable be exposed as an environment variable?
Note that every environment variable is also exposed as a shell variable, but the inverse is not true: shell variables are only visible to the current shell and its subshells, but not to child processes, such as external utilities and (non-sourced) scripts (unless they’re marked as environment variables with export or declare -x ).
What happens when you Echo a variable in Bash?
By default it contains space, tab, and newline characters: This means that when shell is doing field splitting (or word splitting) it uses all these characters as word separators. This is what happens when referencing a variable without double quotes to echo it ( $var) and thus expected output is altered.
What happens when you Echo a variable without double quotes?
This is what happens when referencing a variable without double quotes to echo it ( $var) and thus expected output is altered. One way to prevent word splitting (besides using double quotes) is to set IFS to null. See http://pubs.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html#tag_02_06_05 :
How to return only the portion of a line after a matching pattern?
So pulling open a file with cat and then using grep to get matching lines only gets me so far when I am working with the particular log set that I am dealing with. It need a way to match lines to a pattern, but only to return the portion of the line after the match. The portion before and after the match will consistently vary.