AWK built-in functions

AWK has the mathematical functions like exp, log, sqrt, sin, cos, atan2, etc. built-in, other built-in functions are:

• length the length of its argument taken as a string, or of$0 if no argument.
• rand random number between 0 and 1
• srand sets seed for rand and returns the previous seed.
• int truncates to an integer value
• substr(s, m, n) the n-character substring of s that begins at position m counted from 1.
• index(s, t) the position in s where the string t occurs, or 0 if it does not.
• match(s, r) the position in s where the regular expression r occurs, or 0 if it does not. The variables RSTART and RLENGTH are set to the position and length of the matched string.
• split(s, a, fs) splits the string s into array elements a[1], a[2], ..., a[n], and returns n. The separation is done with the regular expression fs or with the field separator FS if fs is not given. An empty string as field separator splits the string into one array element per character.
• sub(r, t, s) substitutes t for the first occurrence of the regular expression r in the string s. If s is not given, $0 is used.
• gsub same as sub except that all occurrences of the regular expression are replaced; sub and gsub return the number of replacements.
• sprintf(fmt, expr, ... ) the string resulting from formatting expr ... according to the printf format fmt.
• system(cmd) executes cmd and returns its exit status.
• tolower(str) returns a copy of str with all upper-case characters translated to their corresponding lower-case equivalents.
• toupper(str) returns a copy of str with all lower-case characters translated to their corresponding upper-case equivalents.