awk (gawk) #

gawk OPTIONS -f PROGRAM-FILE [--] FILE...
gawk OPTIONS [--] PROGRAM-TEXT FILE...

-F fs
--field-separator fs
    The input field separator
-v var=val
--assign var=val
    Assign the value val to the variable var
-V
--version
    Print version

FS
    The input field separator
RS
    The input record separator
OFS
    The output field separator
ORS
    THE output record separator
OFMT
    The output format for numbers, "%.6g", by default.
FIELDWIDTHS
    Fixed width for input fields
FPAT
    A regular expression for input fields (overrided by FS or FIELDWIDTHS).
IGNORECASE
    Controls the case-sensitivity of all regular expression and string operations.

ENVIRON
    An  array  containing the values of the current environment (e.g., ENVIRON["HOME"] might be "/home/arnold").
FNR
    The input record number in the current input file.
NF
    The number of fields in the current input record.
NR
    The total number of input records seen so far.

if (condition) statement [ else statement ]
while (condition) statement
do statement while (condition)
for (expr1; expr2; expr3) statement
for (var in array) statement
break
continue
delete array[index]
delete array
exit [ expression ]
{ statements }
switch (expression) {
    case value|regex : statement
    ...
    [ default: statement ]
}

close(file [, how])
    Close file, pipe or co-process.
getline
    Set $0 from next input record; set NF, NR, FNR, RT.  The getline command returns 1 on success, 0 on end of file, and -1 on an error.
getline <file
    Set $0 from next record of file; set NF, RT.
getline var
    Set var from next input record; set NR, FNR, RT.
getline var <file
    Set var from next record of file, RT.
command | getline [var]
    Run command piping the output either into $0 or var, as above, and RT.
command |& getline [var]
    Run command as a co-process piping the output either into $0 or var, as above, and RT. (command can also be a socket.)
next
    Stop processing the current input record.
nextfile
    Stop  processing the current input file.
print
    Print the current record. The output record is terminated with the value of ORS.
print expr-list
    Print expressions.  Each expression is separated by the value of OFS. The output record is terminated with the value of ORS.
print expr-list >file
    Print expressions on file.
printf fmt, expr-list
    Format and print.
printf fmt, expr-list >file
    Format and print on file.
system(cmd-line)
    Execute  the  command  cmd-line,  and return the exit status.
fflush([file])
    Flush any buffers associated with the open output file or pipe file.

print ... >> file
    Appends output to the file.
print ... | command
    Writes on a pipe.
print ... |& command
    Sends data to a co-process or socket.

-
    The standard input.
/dev/stdin
    The standard input.
/dev/stdout
    The standard output.
/dev/stderr
    The standard error output.
/dev/fd/n
    The file associated with the open file descriptor n.

atan2(y, x)

cos(expr)

exp(expr)

int(expr)

log(expr)

rand()

sin(expr)

sqrt(expr)

srand([expr])

asort(s [, d [, how] ])

asorti(s [, d [, how] ])

gsub(r, s [, t])

index(s, t)

length([s])

match(s, r, [, a])

split(s, a [, r [, seps] ])

sprintf(fmt, expr-list)

substr(s, i [, n])

tolower(str)

toupper(str)

print "You blew it!" > "/dev/stderr"

print "You blew it!" | "cat 1>&2"

json = $1
#json = "{\"text\":\"abc\",\"flag\":\"123\"}"
cmd = "echo '" json "' | jq -r '.text, .flag' | tr '\n' '\t'"
cmd | getline
close(cmd)
print $1 $2

function myfunc(s) {
    print NF ":" s
}
{
    myfunc($1)
}