Bash (Bourne again shell) es un programa informático cuya función consiste en interpretar órdenes, está basado en la shell de Unix y es el intérprete por defecto de la mayoría de las distribuciones de Linux.
Bash contiene una gran variedad de formas de interpretar los recursos del sistema de modo matemático y renderizar los resultados en un formato fácil de entender. Esto es especialmente útil cuando hay la necesidad de optimizar alguno de los recursos por defecto de Linux, como MySQL, servidor de correo, Apache, ect...
En este ejemplo vamos a mirar y analizar los recursos que están en uso de Apache, la memoria que está siendo utilizada por los procesos actuales de Apache, las posibles conexiones disponibles y el uso general de memoria de la máquina.
Hemos elegido este script para el tutorial porque utilizamos las funciones matématicas internas de Bash para números enteros. Utilizamos llamadas a BC (módulo de cálculos de Bash) para números reales y utilizamos expresiones regulares y manipulación de arrays. Veremos sentencias condicionales, uso de bucles WHILE y uso de funciones.
Código :
#!/bin/env bash # Definimos la función function doStat() { # Define variables # Iniciación de variables que vamos a usar cnt=0 cpl=0 di1=1 di2=$((1024*1000)) di3=1024 max=0 statusbar=38 tot=0 ty1="Mb" ty2="Mb" ty3="Mb" ty4="Mb" ty5="Mb" # Compruebo si estamos en un servidor con cPanel instalado, ya hay ligeras variaciones en el formato de "TOP" # Aquí vemos una sentencia condicional, siempre empieza por if, hay que observar que despúes del corchete "[" siempre hay que dejar un espacio. Igualmente, hay que dejar un espacio antes del corchete de cierre. if [ -d /usr/local/cpanel ]; then cpl=1 di1=100 fi # Cerramos la sentencia con "fi" # Comprobar si la memoria encontrada en top contiene el caracter "m" para saber que si los resultados se presentan en Mb o Kb mck=`top -b -c -n 1|grep -E "apache|httpd"|awk '{print$6}'|grep -c m` if [ $mck -ne 0 ]; then di1=1 fi # Cargamos en la variable fre la memoria disponible fre=`grep -E "^MemFree:" /proc/meminfo|awk '{print$2}'` # Cargamos en la variable total la memoria instalada total=`grep -E "^MemTotal:" /proc/meminfo|awk '{print$2}'` # Cargamos en mem la memoria usada por Apache. La sacamos de la función top. mem=`top -b -c -n 1|grep -E "apache|httpd"|grep -v grep | awk '{print$6}'|sed -e 's/[a-zA-Z]//g'` # Bucle para mirar cada proceso y calcular ( por proceso ) # avg - media # max - máxima memoria usada # tot - total de memoria usada for m2 in $mem do # Comprobamos si la memoria es un valor entero o un valor real. Aquí usamos una expresión regular en la condicional. if [[ $m2 =~ ^[0-9]{1,3}\.[0-9]{1,3}$ ]]; then #IFS es el valor interno de Bash para el separador de variables internas OIFS=IFS IFS='.' m2=($m2) IFS=$OIFS # La parte real del número la guardo en m1 m1=${m2[1]} # La parte entera la guardo en m2 m2=${m2[0]} # Miramos el número de caracteres que hay en la parte real. Para hacer las conversiones m3=${#m1} m4=10 if [ $m3 -eq 2 ]; then m4=100; fi if [ $m3 -eq 3 ]; then m4=1000; fi # Convertimos a decimal m3=$(((m1*1024)/m4)) # Calculamos tamaño del decimal m2=$(((m2*1024)+m3)) fi # Fin de la comprobación de números reales m=$((m2/di1)) # Cargamos en max el proceso que más memoria ocupa if [ $m -gt $max ]; then max=$m fi # Incrementamos contador y total cnt=$((cnt+1)) tot=$((tot+m)) avg=$((tot/cnt)) done # Fin del bucle mxu=$((tot*1024)) # Comprobamos la media y evitamos la división por cero if [ $avg -eq 0 ]; then avg=1 fi # Obtenemos el número total de los procesos de apache # escuchando o conectado cnt=`lsof -i :80|grep -iE "esta|ist|esc"|wc -l` # Calculamos los procesos disponibles de la máquina ava=$(((fre/avg)/100)) wst=$(((fre/max)/100)) # Aquí usamos BC. Necesitamos un número real y bash no permite operaciones con estos de forma interna pct=`echo "scale=2;($fre/$total)*100"|bc` out=`echo "scale=2;($pct/100)*$statusbar"|bc|awk -F\. '{print$1}'` # Ajustamos para cPanel si es necesario if [ $cpl ] && [ "$out" == '' ]; then out=0 fi # Calculamos el uso de la memoria y convertimos a Gb si es necesario if [ $fre -ge $di2 ]; then ty1="Gb" fre=`echo "scale=2;$fre/$di2"|bc` else if [ $fre -ge $di3 ]; then fre=`echo "scale=2;$fre/$di3"|bc` fi fi if [ $mxu -ge $di2 ]; then ty2="Gb" mxu=`echo "scale=2;$mxu/$di2"|bc` else if [ $mxu -ge $di3 ]; then mxu=`echo "scale=2;$mxu/$di3"|bc` fi fi if [ $total -ge $di2 ]; then ty3="Gb" total=`echo "scale=2;$total/$di2"|bc` fi if [ $avg -ge $di2 ]; then ty4="Gb" avg=`echo "scale=2;$avg/$di2"|bc` fi if [ $max -ge $di2 ]; then ty5="Gb" max=`echo "scale=2;$max/$di2"|bc` fi # Bucle para mostrar una barra de estado sloop=$statusbar statusbar=$((statusbar+3)) nline=`seq -s "=" $statusbar|sed 's/[0-9]//g'` # Mostramos resultados printf "%s\n" $nline printf "Apache processes and memory usage.\n" printf "%s\n" $nline printf "Total installed memory: %s%s\n" $total $ty3 printf "Availiable memory: %s%s\n" $fre $ty1 printf "Free percentile: %s\45\n" $pct # Mostramos la memoria usada en la barra de estado. Observamos que en el bucle while, los corchetes llevan sus espacios después y antes, como en el if que hemos descrito antes. printf "Status bar:\n|" while [ $sloop -ge 1 ]; do cc="-" if [ $sloop -ge $out ]; then cc="+" fi printf "%s" $cc sloop=$((sloop-1)) done printf "|\n" printf "%s\n" $nline printf "Current usage\n" printf "%s\n" $nline printf "Current processes: %d\n" $cnt printf "Average memory:\t %s%s\n" $avg $ty4 printf "Maximum memory:\t %s%s\n" $max $ty5 printf "Overall memory:\t %s%s\n" $mxu $ty2 printf "%s\n" $nline printf "Projected usage\n" printf "%s\n" $nline printf "Concurrent best: %d more connection(s)\n" $ava printf "Concurrent worst: %d more connection(s)\n" $wst printf "%s\n" $nline } # Fin de la función # Ejecutamos la función doStat
El resultado mostrado quedaría más o menos así:
Código :
======================================== Apache processes and memory usage. ======================================== Total installed memory: 4.09Gb Availiable memory: 3.31Gb Free percentile: 80.00% Status bar: |+++++++++-----------------------------| ======================================== Current usage ======================================== Current processes: 28 Average memory: 76Mb Maximum memory: 80Mb Overall memory: 1.99Gb ======================================== Projected usage ======================================== Concurrent best: 446 more connection(s) Concurrent worst: 424 more connection(s) ========================================
Espero vuestros comentarios y sugerencias. Si os gusta, seguiremos publicando artículos sobre el uso de Bash
¿Sabes SQL? ¿No-SQL? Aprende MySQL, PostgreSQL, MongoDB, Redis y más con el Curso Profesional de Bases de Datos que empieza el martes, en vivo.
Por Nico el 02 de Octubre de 2012
Por pedro-vk el 02 de Octubre de 2012
Por Juan el 03 de Octubre de 2012
Por dvpareja el 03 de Octubre de 2012
Como bien se ha dicho, es raro ver esto en Cristalab. La razón principal de hacerlo es que esta web ha sido mi lugar de referencia para el aprendizaje durante los últimos años, y quiero aportar mi granito de arena para que siga siendo el punto de encuentro de gente que empieza o que quiere ampliar sus conocimientos en este mundo.
P.D.: Eso es lo grande de nuestro idioma, su riqueza lingüística. La RAE, en su Diccionario Panhispánico de dudas especifica sus dos formas. En España se emplea solo monitorizar, mientras que en América se usa casi exclusivamente monitorear. Así que ya sabemos de donde somos cada uno
Saludos
Por Shanti el 09 de Abril de 2013
Por Shanti el 09 de Abril de 2013
4: Syntax error: "(" unexpected
Hace referencia a la linea 4 donde esta la función, pero esta correctamente, no entiendo por no funciona. Gracias por cualquier ayuda.
[email protected]
Por Xeleneo el 18 de Marzo de 2014
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Por José el 31 de Enero de 2018
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