{"id":33494,"date":"2019-10-31T21:52:52","date_gmt":"2019-10-31T18:52:52","guid":{"rendered":"https:\/\/prohoster.info\/blog\/sem-neozhidannyh-peremennyh-bash\/"},"modified":"2019-10-31T21:52:52","modified_gmt":"2019-10-31T18:52:52","slug":"sem-neozhidannyh-peremennyh-bash","status":"publish","type":"post","link":"https:\/\/prohoster.info\/et\/blog\/administrirovanie\/sem-neozhidannyh-peremennyh-bash","title":{"rendered":"Seitsme ootamatu Bash'i muutuja.","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

J\u00e4tkates m\u00e4rkmete seeriat v\u00e4hem tuntud<\/a><\/noindex> funktsioonidest<\/a><\/noindex> bash, tutvustan teile seitset muutujat, millest te v\u00f5isite mitte teada.<\/p>\n

1) PROMPT_COMMAND<\/code><\/h4>\n

\nV\u00f5ib-olla olete juba kursis, kuidas k\u00e4surea kutses n\u00e4idata erinevat kasulikku teavet, kuid mitte k\u00f5ik ei tea, et iga kord, kui kutset kuvatakse, saab k\u00e4ivitada shelli k\u00e4su.<\/p>\n

T\u00f5epoolest, paljud keerukad kutse manipulaatorid kasutavad seda muutujat, et k\u00e4ivitada k\u00e4ske teabe kogumiseks, mis kuvatakse kutse all.<\/p>\n

Proovige seda uues shellis k\u00e4ivitada ja n\u00e4ete, mis sessiooniga juhtub:<\/p>\n

$ PROMPT_COMMAND='echo -n \"writing the prompt at \" && date'<\/code><\/pre>\n
<\/a><\/noindex><\/p>\n
2) HISTTIMEFORMAT<\/code><\/h4>\n
\nKui k\u00e4ivitada history<\/code> konsoolis, saate loetelu k\u00e4skudest, mis on varem teie kasutajakonto all t\u00e4idetud.<\/p>\n
$ HISTTIMEFORMAT='I ran this at: %d\/%m\/%y %T '<\/code><\/pre>\n
\nKui see muutuja on seadistatud, salvestatakse uued kirjed koos ajaga, nii et v\u00e4ljund n\u00e4eb v\u00e4lja j\u00e4rgmine:<\/p>\n
1871  I ran this at: 01\/05\/19 13:38:07 cat \/etc\/resolv.conf\n1872  I ran this at: 01\/05\/19 13:38:19 curl bbc.co.uk\n1873  I ran this at: 01\/05\/19 13:38:41 sudo vi \/etc\/resolv.conf\n1874  I ran this at: 01\/05\/19 13:39:18 curl -vvv bbc.co.uk\n1876  I ran this at: 01\/05\/19 13:39:25 sudo su -<\/pre>\n
\nFormaat vastab s\u00fcmbolitele, mis on saadaval man date<\/code>.<\/p>\n
3) CDPATH<\/code><\/h4>\n
\nK\u00e4sureas aega s\u00e4\u00e4stmiseks v\u00f5ite kasutada seda muutuja, et katalooge muuta sama lihtsalt nagu k\u00e4skude k\u00e4ivitamine.<\/p>\n
Nagu ka PATH<\/code>, muutuja CDPATH<\/code> esindab kolmandate teede loetelu, mis on eraldatud koolonitega. Kui k\u00e4ivitate k\u00e4su cd<\/code> suhtelise teega (st ilma kaldkriipsuta alguses), otsib shell vaikimisi sobivaid nimesid teie kohalikust kaustast. CDPATH<\/code> otsib teed, mille olete m\u00e4\u00e4ranud kaustaks, kuhu soovite minna.<\/p>\n
Kui seadistate CDPATH<\/code> nii:<\/p>\n
$ CDPATH=\/:\/lib<\/code><\/pre>\n
\nja seej\u00e4rel sisestate:<\/p>\n
$ cd \/home\n$ cd tmp<\/code><\/pre>\n
\nsiis j\u00f5uate alati \/tmp<\/code> s\u00f5ltumata sellest, kus te olete.<\/p>\n
Kuid olge ettevaatlik, sest kui te ei m\u00e4\u00e4ratle kohaliku (.<\/code>) kausta nimekirjas, siis ei saa te luua \u00fchtegi teist kausta tmp<\/code> ja minna sellele nagu tavaliselt:<\/p>\n
$ cd \/home\n$ mkdir tmp\n$ cd tmp\n$ pwd\n\/tmp<\/code><\/pre>\n
\nUps!<\/p>\n
See tundub segadusena, mida tundsin, kui m\u00f5istsin, et kohaliku kausta ei olnud rohkem tuntud muutuja PATH<\/code>\u2026 aga peate seda tegema PATH muutuja puhul, sest v\u00f5idakse petta, k\u00e4ivitades vale k\u00e4su mingist allalaaditud koodist.<\/p>\n
Minu seab alguspunktiks:<\/p>\n
CDPATH=.:\/space:\/etc:\/var\/lib:\/usr\/share:\/opt<\/code><\/pre>\n
<\/p>\n
4) SHLVL<\/code><\/h4>\n
\nKas olete kunagi m\u00f5elnud, et exit<\/code> viib teid praegusest bash-keskkonnast teise \"vanema\" keskkonda v\u00f5i lihtsalt sulgeb konsooli akna t\u00e4ielikult?<\/p>\n
See muutuja j\u00e4lgib, kui s\u00fcgavale olete bash-keskkonnas s\u00fcvenenud. Uue terminali loomisel on see seadistatud v\u00e4\u00e4rtusele 1:<\/p>\n
$ echo $SHLVL\n1<\/code><\/pre>\n
\nSeej\u00e4rel, kui k\u00e4ivitada teine shell-protsess, suureneb number:<\/p>\n
$ bash\n$ echo $SHLVL\n2<\/code><\/pre>\n
\nSee v\u00f5ib olla v\u00e4ga kasulik skriptides, kus te pole kindel, kas peaksite v\u00e4ljuma v\u00f5i mitte, v\u00f5i j\u00e4lgida, kus te s\u00fcvenemise kaudu viibite.<\/p>\n
5) LINENO<\/code><\/h4>\n
\nSama kehtib ka praeguse oleku anal\u00fc\u00fcsimiseks ja t\u00f5rkeotsinguks, kasulik on muutuja LINENO<\/code>, mis n\u00e4itab, mitu k\u00e4sku on seansi jooksul seni t\u00e4idetud:<\/p>\n
$ bash\n$ echo $LINENO\n1\n$ echo $LINENO\n2<\/code><\/pre>\n
\nSeda kasutatakse k\u00f5ige sagedamini skriptide t\u00f5rkeotsinguks. Selliste ridade lisamine nagu echo DEBUG:$LINENO<\/code>, saate kiiresti kindlaks teha, kus skriptis viibite (v\u00f5i ei ole).<\/p>\n
6) REPLY<\/code><\/h4>\n
\nKui te, nagu mina, kirjutate tavaliselt sellist koodi:<\/p>\n
$ read input\necho do something with $input<\/code><\/pre>\n
\nsiis v\u00f5ib \u00fcllatuseks olla, et muutuja loomise p\u00e4rast ei pea \u00fcldse muretsema:<\/p>\n
$ read\necho do something with $REPLY<\/code><\/pre>\n
\nSee teeb sama asja.<\/p>\n
7) TMOUT<\/code><\/h4>\n
\nEttev\u00f5tte serverites liiga kaua viibimise v\u00e4ltimiseks turvalisuse huvides v\u00f5i juhuslikult ohtlikku terminali midagi k\u00e4ivitades toimib selle muutuja seadmine kaitsemehhanismina.<\/p>\n
Kui mingit sisendit ei tehtud kindlaksm\u00e4\u00e4ratud sekundi jooksul, toimub v\u00e4ljalogimine.<\/p>\n
See on alternatiiv sleep 1 && exit<\/code>:<\/p>\n
$ TMOUT=1<\/code><\/pre>\n
Allikas: habr.com<\/a><\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"
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Tegelikult on palju keerulisi kutse manipulaatoreid.","canonical_url":"https:\/\/prohoster.info\/et\/blog\/administrirovanie\/sem-neozhidannyh-peremennyh-bash","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":null,"og:locale":"et_EE","og:site_name":"ProHoster | \u041a\u0443\u043f\u0438\u0442\u044c \u043d\u0430\u0434\u0435\u0436\u043d\u044b\u0439 \u0445\u043e\u0441\u0442\u0438\u043d\u0433 \u0434\u043b\u044f \u0441\u0430\u0439\u0442\u043e\u0432 \u0441 \u0437\u0430\u0449\u0438\u0442\u043e\u0439 \u043e\u0442 DDoS, VPS VDS \u0441\u0435\u0440\u0432\u0435\u0440\u044b","og:type":"article","og:title":"\ud83e\udd47\u0421\u0435\u043c\u044c \u043d\u0435\u043e\u0436\u0438\u0434\u0430\u043d\u043d\u044b\u0445 \u043f\u0435\u0440\u0435\u043c\u0435\u043d\u043d\u044b\u0445 Bash | ProHoster","og:description":"\u041f\u0440\u043e\u0434\u043e\u043b\u0436\u0430\u044f \u0441\u0435\u0440\u0438\u044e \u0437\u0430\u043c\u0435\u0442\u043e\u043a \u043e 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