C

List of C Error Codes (errno.h, errno-base.h)

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Here’s a list of the C error codes in one place.

Error codes located at /usr/include/asm-generic/errno-base.h:

#define EPERM 1 /* Operation not permitted */
#define ENOENT 2 /* No such file or directory */
#define ESRCH 3 /* No such process */
#define EINTR 4 /* Interrupted system call */
#define EIO 5 /* I/O error */
#define ENXIO 6 /* No such device or address */
#define E2BIG 7 /* Argument list too long */
#define ENOEXEC 8 /* Exec format error */
#define EBADF 9 /* Bad file number */
#define ECHILD 10 /* No child processes */
#define EAGAIN 11 /* Try again */
#define ENOMEM 12 /* Out of memory */
#define EACCES 13 /* Permission denied */
#define EFAULT 14 /* Bad address */
#define ENOTBLK 15 /* Block device required */
#define EBUSY 16 /* Device or resource busy */
#define EEXIST 17 /* File exists */
#define EXDEV 18 /* Cross-device link */
#define ENODEV 19 /* No such device */
#define ENOTDIR 20 /* Not a directory */
#define EISDIR 21 /* Is a directory */
#define EINVAL 22 /* Invalid argument */
#define ENFILE 23 /* File table overflow */
#define EMFILE 24 /* Too many open files */
#define ENOTTY 25 /* Not a typewriter */
#define ETXTBSY 26 /* Text file busy */
#define EFBIG 27 /* File too large */
#define ENOSPC 28 /* No space left on device */
#define ESPIPE 29 /* Illegal seek */
#define EROFS 30 /* Read-only file system */
#define EMLINK 31 /* Too many links */
#define EPIPE 32 /* Broken pipe */
#define EDOM 33 /* Math argument out of domain of func */
#define ERANGE 34 /* Math result not representable */

Error codes located at /usr/include/asm-generic/errno.h:

#include

#define EDEADLK 35 /* Resource deadlock would occur */L
#define ENAMETOOLONG 36 /* File name too long */
#define ENOLCK 37 /* No record locks available */
#define ENOSYS 38 /* Function not implemented */
#define ENOTEMPTY 39 /* Directory not empty */
#define ELOOP 40 /* Too many symbolic links encountered */
#define EWOULDBLOCK EAGAIN /* Operation would block */
#define ENOMSG 42 /* No message of desired type */
#define EIDRM 43 /* Identifier removed */
#define ECHRNG 44 /* Channel number out of range */
#define EL2NSYNC 45 /* Level 2 not synchronized */
#define EL3HLT 46 /* Level 3 halted */
#define EL3RST 47 /* Level 3 reset */
#define ELNRNG 48 /* Link number out of range */
#define EUNATCH 49 /* Protocol driver not attached */
#define ENOCSI 50 /* No CSI structure available */
#define EL2HLT 51 /* Level 2 halted */
#define EBADE 52 /* Invalid exchange */
#define EBADR 53 /* Invalid request descriptor */
#define EXFULL 54 /* Exchange full */
#define ENOANO 55 /* No anode */
#define EBADRQC 56 /* Invalid request code */
#define EBADSLT 57 /* Invalid slot */
#define EDEADLOCK EDEADLK
#define EBFONT 59 /* Bad font file format */
#define ENOSTR 60 /* Device not a stream */
#define ENODATA 61 /* No data available */
#define ETIME 62 /* Timer expired */
#define ENOSR 63 /* Out of streams resources */
#define ENONET 64 /* Machine is not on the network */
#define ENOPKG 65 /* Package not installed */
#define EREMOTE 66 /* Object is remote */
#define ENOLINK 67 /* Link has been severed */
#define EADV 68 /* Advertise error */
#define ESRMNT 69 /* Srmount error */
#define ECOMM 70 /* Communication error on send */
#define EPROTO 71 /* Protocol error */
#define EMULTIHOP 72 /* Multihop attempted */
#define EDOTDOT 73 /* RFS specific error */
#define EBADMSG 74 /* Not a data message */
#define EOVERFLOW 75 /* Value too large for defined data type */
#define ENOTUNIQ 76 /* Name not unique on network */
#define EBADFD 77 /* File descriptor in bad state */
#define EREMCHG 78 /* Remote address changed */
#define ELIBACC 79 /* Can not access a needed shared library */
#define ELIBBAD 80 /* Accessing a corrupted shared library */
#define ELIBSCN 81 /* .lib section in a.out corrupted */
#define ELIBMAX 82 /* Attempting to link in too many shared libraries */
#define ELIBEXEC 83 /* Cannot exec a shared library directly */
#define EILSEQ 84 /* Illegal byte sequence */
#define ERESTART 85 /* Interrupted system call should be restarted */
#define ESTRPIPE 86 /* Streams pipe error */
#define EUSERS 87 /* Too many users */
#define ENOTSOCK 88 /* Socket operation on non-socket */
#define EDESTADDRREQ 89 /* Destination address required */
#define EMSGSIZE 90 /* Message too long */
#define EPROTOTYPE 91 /* Protocol wrong type for socket */
#define ENOPROTOOPT 92 /* Protocol not available */
#define EPROTONOSUPPORT 93 /* Protocol not supported */
#define ESOCKTNOSUPPORT 94 /* Socket type not supported */
#define EOPNOTSUPP 95 /* Operation not supported on transport endpoint */
#define EPFNOSUPPORT 96 /* Protocol family not supported */
#define EAFNOSUPPORT 97 /* Address family not supported by protocol */
#define EADDRINUSE 98 /* Address already in use */
#define EADDRNOTAVAIL 99 /* Cannot assign requested address */
#define ENETDOWN 100 /* Network is down */
#define ENETUNREACH 101 /* Network is unreachable */
#define ENETRESET 102 /* Network dropped connection because of reset */
#define ECONNABORTED 103 /* Software caused connection abort */
#define ECONNRESET 104 /* Connection reset by peer */
#define ENOBUFS 105 /* No buffer space available */
#define EISCONN 106 /* Transport endpoint is already connected */
#define ENOTCONN 107 /* Transport endpoint is not connected */
#define ESHUTDOWN 108 /* Cannot send after transport endpoint shutdown */
#define ETOOMANYREFS 109 /* Too many references: cannot splice */
#define ETIMEDOUT 110 /* Connection timed out */
#define ECONNREFUSED 111 /* Connection refused */
#define EHOSTDOWN 112 /* Host is down */
#define EHOSTUNREACH 113 /* No route to host */
#define EALREADY 114 /* Operation already in progress */
#define EINPROGRESS 115 /* Operation now in progress */
#define ESTALE 116 /* Stale file handle */
#define EUCLEAN 117 /* Structure needs cleaning */
#define ENOTNAM 118 /* Not a XENIX named type file */
#define ENAVAIL 119 /* No XENIX semaphores available */
#define EISNAM 120 /* Is a named type file */
#define EREMOTEIO 121 /* Remote I/O error */
#define EDQUOT 122 /* Quota exceeded */
#define ENOMEDIUM 123 /* No medium found */
#define EMEDIUMTYPE 124 /* Wrong medium type */
#define ECANCELED 125 /* Operation Canceled */
#define ENOKEY 126 /* Required key not available */
#define EKEYEXPIRED 127 /* Key has expired */
#define EKEYREVOKED 128 /* Key has been revoked */
#define EKEYREJECTED 129 /* Key was rejected by service */

/* for robust mutexes */
#define EOWNERDEAD 130 /* Owner died */
#define ENOTRECOVERABLE 131 /* State not recoverable */
#define ERFKILL 132 /* Operation not possible due to RF-kill */
#define EHWPOISON 133 /* Memory page has hardware error */

Grep 101: 7 Basic Uses of Grep

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  1.  The most basic grep usage is to try to find a single string inside of a single text file.
    For example, if you wanted to find the text “Bob” inside of hello.txt (note that lower-case bob would not match),
    You could enter the following into the terminal:
    grep “Bob” hello.txt
  2. Let’s say you knew that “Bob” might also be written in lower-case and you wanted to find all matches for both upper and lower case.  In this scenario, you would add the “-i” flag to your grep search:
    grep -i “Bob” hello.txt
    Note you could just as easily do:
    grep -i “bOb” hello.txt
    and it would have the exact same effect.  The “i” in -i stands for “case-insensitive.”  Match regardless of upper-case or lower-case.
  3. How to show only the first N number of matches with grep.
    Let’s say you know there will be A LOT of Bobs in your file but you only care to see the first 10 of them.
    Use the “-m” flag while searching with grep:
    grep -m 10 “Bob” hello.txt
    You can modify the value N = 10 as you desire.  Let’s try 70:
    grep -m 70 “Bob” hello.txt
  4. Reverse grep – how to display all lines that do NOT match the string.
    Now let’s try finding all lines that do NOT include the text “Bob” in them.  We could use the -v flag:
    grep -v “Bob” hello.txt
  5. Matching 2 or 3 or 4 or 5…. different strings with grep:
    Let’s try to find “Alice” OR “Bob” in our file.  This will return all matches for either of the two strings.
    We use the “-e” flag for OR:
    grep -e “Bob” -e “Alice” hello.txt
  6. How to search all files recursively for a match.
    Let’s say you had a directory of thousands of log files and you wanted to see if you could find “Bob” in any  of those.
    You would use the “-r” flag.  I typically pair the “-i” (case-insensitive) flag with this when I’m not sure about the capitalization of the text I’m looking for.
    grep -ir “Bob”
    Note that we didn’t need to include the target files here to search in.  Let’s say we had a special directory that we wanted to limit our search to (rather than being in our current working directory).
    grep -ir “Bob” myDirectoryFullOfLogFiles
  7. Counting the number of matches.
    If you wanted to know how many times the word “Bob” showed up in a file, you could do the following:
    grep -c “Bob” hello.txt

6 Quick Linux “Hacks”

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To start us off, I’ve compiled a small list of Linux commands or pairings of commands:

  1. How to empty the contents of a file
    For example, if you had a log file that you wanted to clear the contents of without actually deleting the file, you could do any of the following:

    • echo “” > myFile.txt
    • dd if=/dev/null of=myfile.txt
    • truncate size=0 myfile.txt
  2. Check if a program exists (e.g. tree)
    which tree
  3. Count all files in a directory inclusively with all sub-directory files included
    ls -R myDir/ | wc -l
  4. Find process details
    ps -ef | grep “my_process”
    ps -ef lists every process on the system using standard syntax and the grep finds the process you are looking for
    Also could do pgrep “my_process” to get the pid of the process if it actually exists
  5. Display all text that doesn’t match a string
    Using the previous example of searching for process details, we could use
    grep -v “not-this-process”
    to display all processes that do not match.
  6. Search for a string of text in a file and count the number of matches
    grep -i “what i’m searching for” | wc -l

 

Introduction

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Hello and welcome!
This is a new technology blog that I’ve created for my own reference and for helping others.  Please take a look at the “About” section for more details.

I’ll be adding a wide variety of tech-related information in my posts to this site.
Just to give you an idea of some things I might post, I could post something like the following:

  1. How various encryption schemes work
  2. How FPGAs work or the history of FPGAs
  3. Schematics for circuits I’ve built for fun personal projects!
  4. Code or links to repositories for software that I’ve built
  5. The math involved for some signal processing
  6. Example code for solving problems
  7. Advice for people entering Engineering / Tech or job-hunting
  8. How to install and set up “xyz” on your “abc” operating system
  9. What virtual memory is / what the Linux kernel is / etc.
  10. Cool / useful Linux terminal commands
  11. Perhaps posts that combine with other hobbies of mine (e.g. how electric guitars or cars work!)
  12. etc., etc., etc!!! 🙂

I hope you enjoy!

Best Regards,
Jeremy