Zaɓi umarni a cikin Linux ana amfani da shi don ƙirƙirar menu mai lamba wanda mai amfani zai iya zaɓar wani zaɓi. Idan mai amfani ya shigar da ingantaccen zaɓi to ya aiwatar da saitin umarni da aka rubuta a cikin zaɓin toshe sannan ya sake tambaya don shigar da lamba, idan zaɓi mara kyau ba ya yin komai.
Lokacin amfani da zaɓi Linux?
zaži () damar a shirye-shirye don saka idanu masu bayanin fayiloli da yawa, jira har sai ɗaya ko fiye na masu siffanta fayil ɗin ya zama “a shirye” don wasu aji na aikin I/O (misali, shigar da zai yiwu).
Menene zaɓin tsarin kiran da ake amfani dashi a cikin Linux?
Zaɓi tsarin kiran tsarin da aikace-aikacen shirye-shiryen kwamfuta (API) a cikin Unix-like da tsarin aiki masu dacewa da POSIX don bincika matsayin masu siffanta fayil na tashoshin shigarwa/fitarwa na buɗewa.. Kiran tsarin zaɓi yayi kama da wurin jefa ƙuri'a da aka gabatar a cikin UNIX System V da kuma tsarin aiki daga baya.
Ta yaya zaɓin aikin ke aiki?
Aikin zaɓi yana toshe tsarin kiran har sai an sami aiki akan kowane ƙayyadadden saiti na masu bayanin fayil, ko kuma har sai lokacin ƙarewar ya ƙare.
Menene zaɓaɓɓen aiki?
Bayanin SQL SELECT ya dawo da saitin sakamakon, daga tebur ɗaya ko fiye. Bayanin SELECT yana dawo da sifili ko fiye da layuka daga ɗaya ko fiye da tebur na bayanai ko ra'ayoyin bayanai. A yawancin aikace-aikace, SELECT shine umarnin da aka fi amfani da shi na harshen sarrafa bayanai (DML).
Menene aikin zaɓi () kira?
zaži () kuma pselect() izini shirin don saka idanu masu bayanin fayil da yawa, jira har sai ɗaya ko fiye na masu bayanin fayil ɗin ya zama “a shirye” don wasu aji na aikin I/O (misali, shigar da mai yiwuwa). ... select() bashi da gardama na sigmask, kuma yana aiki kamar pselect() da ake kira da NULL sigmask.
Menene Fd_set a cikin Linux?
Fd_set shine madaidaicin girman buffer. Yin aiwatar da FD_CLR() ko FD_SET() tare da ƙimar fd mara kyau ko daidai ko girma fiye da FD_SETSIZE zai haifar da halin da ba a bayyana ba. Bugu da ƙari, POSIX yana buƙatar fd ya zama ingantaccen bayanin fayil.
Ta yaya zan yi amfani da zaɓin kiran tsarin?
Server:
- Ƙirƙiri TCP watau Sauraron soket.
- Ƙirƙiri soket na UDP.
- Daure duka soket zuwa adireshin uwar garken.
- Ƙaddamar da saitin sifan don zaɓi kuma ƙididdige iyakar mai siffantawa 2 wanda za mu jira.
- Zaɓi zaɓi kuma sami shirye-shiryen bayanin (TCP ko UDP)
Ana zaɓi () yana tarewa?
Lokacin da kuka dawo don zaɓar () yana toshewa, yana jiran ƙarin bayanai. Duk da haka takwarorinku a wancan gefen haɗin yana jiran amsa ga bayanan da aka aiko. Shirin ku yana ƙarewa har abada. Kuna iya yin aiki a kusa da shi tare da ƙarewar lokaci da irin wannan, amma gabaɗayan batu shine sanya I/O mara hanawa.
Menene epoll a cikin Linux?
epoll da tsarin kernel na Linux yana kira don tsarin sanarwa na I/O mai iya daidaitawa, an fara gabatar da shi a cikin sigar 2.5. … Ayyukansa shine saka idanu masu siffanta fayiloli da yawa don ganin ko I/O zai yiwu akan ɗayansu.
Ta yaya zan zaɓi wasu layuka a cikin R?
Rarraba Layukan Tsarin Bayanai a cikin R
- yanki(): Cire layuka ta matsayi.
- filter(): Cire layuka waɗanda suka dace da takamaiman ma'auni. …
- filter_all(), filter_if () da filter_at(): tace layuka a cikin zaɓi na masu canji. …
- sample_n(): Zaɓi n layuka ba da gangan ba.
- sample_frac(): Zaɓi guntun layuka ba da gangan ba.
Menene zabe da zabe?
jefa kuri'a da zažužžukan gaskiya guda ne masu hikimar sauri: jinkirin. Dukansu biyu suna sarrafa masu bayanin fayil a hanya madaidaiciya. Da yawan masu siffantawa da kuke buƙatar su duba, da sannu a hankali suke samun. … zaži() yana amfani ne kawai (a iyakar) rago uku na bayanai kowane mai siffanta fayil, yayin da zabe() yawanci yana amfani da ragi 64 akan kowane mai siffanta fayil.