Shell - commands 2

zzh@ZZHPC:~$ ifconfig > a.txt
zzh@ZZHPC:~$ ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=53 time=48.7 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=53 time=50.0 ms
64 bytes from 8.8.8.8: icmp_seq=3 ttl=53 time=53.2 ms
64 bytes from 8.8.8.8: icmp_seq=4 ttl=53 time=49.4 ms
64 bytes from 8.8.8.8: icmp_seq=5 ttl=53 time=48.0 ms
^C
--- 8.8.8.8 ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4006ms
rtt min/avg/max/mdev = 47.982/49.851/53.164/1.783 ms
zzh@ZZHPC:~$ ifconfig > b.txt
zzh@ZZHPC:~$ cmp a.txt b.txt
a.txt b.txt differ: byte 1242, line 24
zzh@ZZHPC:~$ cp /usr/bin/ls .
zzh@ZZHPC:~$ cmp /usr/bin/ls ls
zzh@ZZHPC:~$ sha256sum /usr/bin/ls ls
8696974df4fc39af88ee23e307139afc533064f976da82172de823c3ad66f444  /usr/bin/ls
8696974df4fc39af88ee23e307139afc533064f976da82172de823c3ad66f444  ls
zzh@ZZHPC:~$ echo 'aaa' > ls
zzh@ZZHPC:~$ cmp /usr/bin/ls ls
/usr/bin/ls ls differ: byte 1, line 1
zzh@ZZHPC:~$ sha256sum /usr/bin/ls ls
8696974df4fc39af88ee23e307139afc533064f976da82172de823c3ad66f444  /usr/bin/ls
17e682f060b5f8e47ea04c5c4855908b0a5ad612022260fe50e11ecb0cc0ab76  ls

zzh@ZZHPC:~$ diff --help
Usage: diff [OPTION]... FILES
Compare FILES line by line.

Mandatory arguments to long options are mandatory for short options too.
      --normal                  output a normal diff (the default)
  -q, --brief                   report only when files differ
  -s, --report-identical-files  report when two files are the same
  -c, -C NUM, --context[=NUM]   output NUM (default 3) lines of copied context
  -u, -U NUM, --unified[=NUM]   output NUM (default 3) lines of unified context
  -e, --ed                      output an ed script
  -n, --rcs                     output an RCS format diff
  -y, --side-by-side            output in two columns
  -W, --width=NUM               output at most NUM (default 130) print columns
      --left-column             output only the left column of common lines
      --suppress-common-lines   do not output common lines

  -p, --show-c-function         show which C function each change is in
  -F, --show-function-line=RE   show the most recent line matching RE
      --label LABEL             use LABEL instead of file name and timestamp
                                  (can be repeated)

  -t, --expand-tabs             expand tabs to spaces in output
  -T, --initial-tab             make tabs line up by prepending a tab
      --tabsize=NUM             tab stops every NUM (default 8) print columns
      --suppress-blank-empty    suppress space or tab before empty output lines
  -l, --paginate                pass output through 'pr' to paginate it

  -r, --recursive                 recursively compare any subdirectories found
      --no-dereference            don't follow symbolic links
  -N, --new-file                  treat absent files as empty
      --unidirectional-new-file   treat absent first files as empty
      --ignore-file-name-case     ignore case when comparing file names
      --no-ignore-file-name-case  consider case when comparing file names
  -x, --exclude=PAT               exclude files that match PAT
  -X, --exclude-from=FILE         exclude files that match any pattern in FILE
  -S, --starting-file=FILE        start with FILE when comparing directories
      --from-file=FILE1           compare FILE1 to all operands;
                                    FILE1 can be a directory
      --to-file=FILE2             compare all operands to FILE2;
                                    FILE2 can be a directory

  -i, --ignore-case               ignore case differences in file contents
  -E, --ignore-tab-expansion      ignore changes due to tab expansion
  -Z, --ignore-trailing-space     ignore white space at line end
  -b, --ignore-space-change       ignore changes in the amount of white space
  -w, --ignore-all-space          ignore all white space
  -B, --ignore-blank-lines        ignore changes where lines are all blank
  -I, --ignore-matching-lines=RE  ignore changes where all lines match RE

  -a, --text                      treat all files as text
      --strip-trailing-cr         strip trailing carriage return on input

  -D, --ifdef=NAME                output merged file with '#ifdef NAME' diffs
      --GTYPE-group-format=GFMT   format GTYPE input groups with GFMT
      --line-format=LFMT          format all input lines with LFMT
      --LTYPE-line-format=LFMT    format LTYPE input lines with LFMT
    These format options provide fine-grained control over the output
      of diff, generalizing -D/--ifdef.
    LTYPE is 'old', 'new', or 'unchanged'.  GTYPE is LTYPE or 'changed'.
    GFMT (only) may contain:
      %<  lines from FILE1
      %>  lines from FILE2
      %=  lines common to FILE1 and FILE2
      %[-][WIDTH][.[PREC]]{doxX}LETTER  printf-style spec for LETTER
        LETTERs are as follows for new group, lower case for old group:
          F  first line number
          L  last line number
          N  number of lines = L-F+1
          E  F-1
          M  L+1
      %(A=B?T:E)  if A equals B then T else E
    LFMT (only) may contain:
      %L  contents of line
      %l  contents of line, excluding any trailing newline
      %[-][WIDTH][.[PREC]]{doxX}n  printf-style spec for input line number
    Both GFMT and LFMT may contain:
      %%  %
      %c'C'  the single character C
      %c'\OOO'  the character with octal code OOO
      C    the character C (other characters represent themselves)

  -d, --minimal            try hard to find a smaller set of changes
      --horizon-lines=NUM  keep NUM lines of the common prefix and suffix
      --speed-large-files  assume large files and many scattered small changes
      --color[=WHEN]       color output; WHEN is 'never', 'always', or 'auto';
                             plain --color means --color='auto'
      --palette=PALETTE    the colors to use when --color is active; PALETTE is
                             a colon-separated list of terminfo capabilities

      --help               display this help and exit
  -v, --version            output version information and exit

FILES are 'FILE1 FILE2' or 'DIR1 DIR2' or 'DIR FILE' or 'FILE DIR'.
If --from-file or --to-file is given, there are no restrictions on FILE(s).
If a FILE is '-', read standard input.
Exit status is 0 if inputs are the same, 1 if different, 2 if trouble.

Report bugs to: bug-diffutils@gnu.org
GNU diffutils home page: <https://www.gnu.org/software/diffutils/>
General help using GNU software: <https://www.gnu.org/gethelp/>

zzh@ZZHPC:~$ patch --help
Usage: patch [OPTION]... [ORIGFILE [PATCHFILE]]

Input options:

  -p NUM  --strip=NUM  Strip NUM leading components from file names.
  -F LINES  --fuzz LINES  Set the fuzz factor to LINES for inexact matching.
  -l  --ignore-whitespace  Ignore white space changes between patch and input.

  -c  --context  Interpret the patch as a context difference.
  -e  --ed  Interpret the patch as an ed script.
  -n  --normal  Interpret the patch as a normal difference.
  -u  --unified  Interpret the patch as a unified difference.

  -N  --forward  Ignore patches that appear to be reversed or already applied.
  -R  --reverse  Assume patches were created with old and new files swapped.

  -i PATCHFILE  --input=PATCHFILE  Read patch from PATCHFILE instead of stdin.

Output options:

  -o FILE  --output=FILE  Output patched files to FILE.
  -r FILE  --reject-file=FILE  Output rejects to FILE.

  -D NAME  --ifdef=NAME  Make merged if-then-else output using NAME.
  --merge  Merge using conflict markers instead of creating reject files.
  -E  --remove-empty-files  Remove output files that are empty after patching.

  -Z  --set-utc  Set times of patched files, assuming diff uses UTC (GMT).
  -T  --set-time  Likewise, assuming local time.

  --quoting-style=WORD   output file names using quoting style WORD.
    Valid WORDs are: literal, shell, shell-always, c, escape.
    Default is taken from QUOTING_STYLE env variable, or 'shell' if unset.

Backup and version control options:

  -b  --backup  Back up the original contents of each file.
  --backup-if-mismatch  Back up if the patch does not match exactly.
  --no-backup-if-mismatch  Back up mismatches only if otherwise requested.

  -V STYLE  --version-control=STYLE  Use STYLE version control.
    STYLE is either 'simple', 'numbered', or 'existing'.
  -B PREFIX  --prefix=PREFIX  Prepend PREFIX to backup file names.
  -Y PREFIX  --basename-prefix=PREFIX  Prepend PREFIX to backup file basenames.
  -z SUFFIX  --suffix=SUFFIX  Append SUFFIX to backup file names.

  -g NUM  --get=NUM  Get files from RCS etc. if positive; ask if negative.

Miscellaneous options:

  -t  --batch  Ask no questions; skip bad-Prereq patches; assume reversed.
  -f  --force  Like -t, but ignore bad-Prereq patches, and assume unreversed.
  -s  --quiet  --silent  Work silently unless an error occurs.
  --verbose  Output extra information about the work being done.
  --dry-run  Do not actually change any files; just print what would happen.
  --posix  Conform to the POSIX standard.

  -d DIR  --directory=DIR  Change the working directory to DIR first.
  --reject-format=FORMAT  Create 'context' or 'unified' rejects.
  --binary  Read and write data in binary mode.
  --read-only=BEHAVIOR  How to handle read-only input files: 'ignore' that they
                        are read-only, 'warn' (default), or 'fail'.

  -v  --version  Output version info.
  --help  Output this help.

Report bugs to <bug-patch@gnu.org>.

zzh@ZZHPC:~$ echo 'aaa' > a.txt
zzh@ZZHPC:~$ echo 'bbb' > b.txt
zzh@ZZHPC:~$ diff a.txt b.txt
1c1
< aaa
---
> bbb
zzh@ZZHPC:~$ echo 'AAA' >> a.txt
zzh@ZZHPC:~$ diff a.txt b.txt
1,2c1
< aaa
< AAA
---
> bbb
zzh@ZZHPC:~$ diff a.txt b.txt > a_b_diff.txt
zzh@ZZHPC:~$ patch a.txt a_b_diff.txt
patching file a.txt
zzh@ZZHPC:~$ cat a.txt
bbb
zzh@ZZHPC:~$ echo 'BBB' >> b.txt
zzh@ZZHPC:~$ diff a.txt b.txt
1a2
> BBB
zzh@ZZHPC:~$ diff a.txt b.txt > a_b_diff.txt
zzh@ZZHPC:~$ patch a.txt a_b_diff.txt
patching file a.txt
zzh@ZZHPC:~$ cat a.txt
bbb
BBB