Learn AWK by Examples
Print all users in /etc/passwd start with a, c, or d
$ awk -F: '
/^[acd]/ {
print $1
}' /etc/passwd
daemon
colord
avahi-autoipd
avahi
chihung
Process stdin based on patterns as range
$ echo 'BEGIN
abc
def
END
junk
junk
START
pqrst
uvwxyz
STOP' | awk '
/START/,/STOP/ { print "-->" $0 }
/BEGIN/,/END/ { print "==>" $0 }
'
==>BEGIN
==>abc
==>def
==>END
-->START
-->pqrst
-->uvwxyz
-->STOP
Print 10 random number 10<=N<20, use /dev/null as a dummy input file
$ awk -v n=10 -v start=10 -v end=20 '
BEGIN {
srand()
for (i=1; i<=n; ++i) {
printf("%d\n", start+rand()*(end-start))
}
}' /dev/null
17
13
15
19
10
11
19
13
11
19
Count by file types in current directory
$ ls -l |
awk '
BEGIN {
dirs=0
files=0
socks=0
links=0
}
/total/ { next }
/^d/ { ++dirs }
/^-/ { ++files }
/^s/ { ++socks }
/^l/ { ++links }
END { print "dirs=" dirs, "files=" files, "socks=" socks, "links=" links }
'
dirs=3 files=10 socks=0 links=0
Count by file types in current directory (using array)
$ ls -l |
awk '
$1 != "total" {
c1=substr($1,1,1)
++s[c1]
}
END {
printf("dirs=%d files=%d socks=%d links=%d\n",
s["d"], s["-"], s["s"], s["l"])
}
'
dirs=3 files=10 socks=0 links=0
Calculate total size of all .gz files in /usr/share directory
$ find /usr/share -type f -name "*.gz" -ls |
awk '
{
s+=$7
}
END {
printf("%.2lf MB\n", s/(1024*1024))
}
'
63.08 MB
Count files by users in /home directory
$ find /home -mount -type f -ls |
awk '
{
++count[$5]
size[$5]+=$7
}
END {
for ( i in count ) {
printf("User=%s Count=%d Size=%s\n", i, count[i], size[i])
}
}
'
User=chihung Count=16301 Size=6346658343
User=root Count=10 Size=80109
Print all users start with e, f, g with their corresponding group name. Group id to name mapping is stored in the gid2name array by processing the first file /etc/group. (Note: I present two similar ways to do the same task)
$ awk -F: '
NR==FNR {
gid2name[$3]=$1
}
NR>FNR && /^[e-g]/ {
print $1, gid2name[$4]
}' /etc/group /etc/passwd
games games
gnats gnats
gdm gdm
games games
gnats gnats
gdm gdm
$ awk -F: '
FILENAME=="/etc/group" {
gid2name[$3]=$1
}
FILENAME=="/etc/passwd" && /^[e-g]/ {
print $1, gid2name[$4]
}' /etc/group /etc/passwd
games games
gnats gnats
gdm gdm
games games
gnats gnats
gdm gdm
Count all file extensions in /usr/include directory
find /usr/include -mount -type f |
$ awk -F/ '
{
basename=$NF
n=split(basename, arr, ".")
if ( n>1 ) {
ext=arr[n]
++summary[ext]
}
}
END {
for ( i in summary ) {
print i, summary[i]
}
}
'
h 4335
def 1
x 17
hpp 245
c 6
tcc 37
Multi-line record with blank line(s) as separator
$ cat ~/.mozilla/firefox/profiles.ini
[General]
StartWithLastProfile=1
[Profile0]
Name=default
IsRelative=1
Path=5d0x3te1.default
$ awk '
BEGIN {
FS="\n"
RS=""
}
{
for ( i=1; i<=NF; ++i ) {
print "NR=" NR, "NF=" i, "Data=" $i
}
}' ~/.mozilla/firefox/profiles.ini
NR=1 NF=1 Data=[General]
NR=1 NF=2 Data=StartWithLastProfile=1
NR=2 NF=1 Data=[Profile0]
NR=2 NF=2 Data=Name=default
NR=2 NF=3 Data=IsRelative=1
NR=2 NF=4 Data=Path=5d0x3te1.default
Print all the section headers in a .ini file with function definition to remove square brackets
$ cat ~/.mozilla/firefox/profiles.ini
[General]
StartWithLastProfile=1
[Profile0]
Name=default
IsRelative=1
Path=5d0x3te1.default
$ awk '
function rmsq(n) {
gsub("\\[","",n)
gsub("]","",n)
return n
}
BEGIN {
FS="\n"
RS=""
}
{
print rmsq($1)
}' ~/.mozilla/firefox/profiles.ini
General
Profile0
Labels: awk
posted by chihungchan at 11:23 PM
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