Linux input-output-redirect Stdin/stdout/stderr

redirect

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1. redirect

Standard input

Standard output

Error output

[Email protected] kkk]#CatAaa.SH#!/bin/Basha=1 while[$a-le5 ] DoUseradd user$a let a++ Done[email protected] kkk]#./aaa.SH[email protected] kkk]#Tail/etc/passwdtcpdump:x: the: the::/:/sbin/nologinsky:x: -: -: sky:/home/sky:/bin/bashserver:x:501:501::/home/server:/bin/bashclient:x:502:502::/home/client:/bin/bashdhcpd:x:177:177:D HCP server:/:/sbin/nologinuser1:x:503:503::/home/user1:/bin/bashuser2:x:504:504::/home/user2:/bin/bashuser3:x:505:505::/home/user3:/bin/bashuser4:x:506:506::/home/user4:/bin/bashuser5:x:507:507::/home/user5:/bin/Bash[[email protected] kkk]#CatAaa1.SH#!/bin/Basha=1 while[$a-le5 ] Do   Echo "111"|passwd--stdin user$a//Standard input let a++ Done[email protected] kkk]#./aaa1.SHchange the password for the user user1. passwd: All the authentication tokens have been successfully updated. Change the password for the user user2. passwd: All the authentication tokens have been successfully updated. Change the password for the user User3. passwd: All the authentication tokens have been successfully updated. Change the password for the user user4. passwd: All the authentication tokens have been successfully updated. Change the password for the user user5. passwd: All the authentication tokens have been successfully updated.

[Email protected] kkk]#Cat 1. Txt//Standard Output11111111[email protected] kkk]#Cat  One. txt//standard Error OutputCat: One. txt: No file or directory [[email protected] kkk]#[[email protected] kkk]#Cat 1. Txt One. txt11111111Cat: One. txt: No file or directory [[email protected] kkk]#Cat 1. Txt One. txt >3. txt//standard output recorded at 3.TX, error output not recordedCat: One. txt: No file or directory [[email protected] kkk]#[[email protected] kkk]#Cat 3. txt11111111[email protected] kkk]#Cat 1. Txt One. txt1>4. Txt2>5. Txt[[email protected] kkk]#Cat 4. Txt//standard output 1 recorded in 4. TXT11111111[email protected] kkk]#Cat 5. Txt//error Output 2 recorded in 5. TXTCat: One. txt: No file or directory [[email protected] kkk]#

[Email protected] kkk]#CatTest.SH#!/bin/BashPing-C3 192.168.10.128 1>/dev/NULLif[$?-eq0 ]   Then  Echo "The host is up!"fi[email protected] kkk]#./test.SHThe host is up!//standard output of ping ignored[Email protected] kkk]#VITest.SH[email protected] kkk]#CatTest.SH#!/bin/BashPing-C3 192.168.10.128if[$?-eq0 ]   Then  Echo "The host is up!"fi[email protected] kkk]#./test.SHPING192.168.10.128(192.168.10.128) About( -) bytes of data. -Bytes from192.168.10.128: icmp_seq=1Ttl= -  Time=0.964Ms -Bytes from192.168.10.128: icmp_seq=2Ttl= -  Time=0.448Ms -Bytes from192.168.10.128: icmp_seq=3Ttl= -  Time=0.467Ms---192.168.10.128 PingStatistics---3Packets Transmitted,3Received0% packet loss, Time2003msrtt min/avg/max/mdev =0.448/0.626/0.964/0.239MS The host is up!//all standard outputs are recorded[Email protected] kkk]#

Linux input-output-redirect Stdin/stdout/stderr