trdsql stdin
stdin
trdsql can receive data from standard input like other UNIX tools. However, you need to specify the table name in SQL syntax. When using standard input, use “-” or “stdin”.
cat test.csv|trdsql -icsv "SELECT * FROM -"
apple,100
orange,50
potato,30trdsql receives standard input, but the execution of SQL starts after all standard input is received. Therefore, you cannot receive output from a command that does not end.
Commands that output CSV, LTSV, and JSON can be used directly by using standard input instead of a file name. For example, you can use it as it is by changing the character code to UTF-8 from a file that is not UTF-8, or
nkf -w sjis.csv|trdsql -icsv "SELECT * FROM -"
You can also try processing only the first few lines before processing a large file.
head -100 big.csv|trdsql -icsv "SELECT * FROM -"
In addition, there are many commands that output data that can be treated as table data if interpreted as a space-separated output in UNIX commands.
For example, the ps command,
$ ps
PID TTY TIME CMD
1157 pts/3 00:00:00 ps
22590 pts/3 00:00:03 zsh
has a header and outputs each column (trdsql behaves to interpret consecutive spaces as one delimiter).
Therefore, you can output it in Ascii Table format as follows.
ps|trdsql -ih -id " " -oat "SELECT \`PID\`, \`TTY\`, \`TIME\`, \`CMD\` FROM -"
+-------+-------+----------+--------+
| PID | TTY | TIME | CMD |
+-------+-------+----------+--------+
| 1363 | pts/3 | 00:00:00 | ps |
| 1364 | pts/3 | 00:00:00 | trdsql |
| 22590 | pts/3 | 00:00:03 | zsh |
+-------+-------+----------+--------+stdin with -a
If you use the -a option, you can specify the table name and file type in the SQL syntax.
command | trdsql -ih -id " " -a -
$ ps|trdsql -id " " -ih -a -
The table name is -.
The file type is CSV.
Data types:
+-------------+------+
| column name | type |
+-------------+------+
| \`PID\` | text |
| \`TTY\` | text |
| \`TIME\` | text |
| \`CMD\` | text |
+-------------+------+
Data samples:
+---------+---------+----------+---------+
| \`PID\` | \`TTY\` | \`TIME\` | \`CMD\` |
+---------+---------+----------+---------+
| 3168 | pts/0 | 00:00:00 | ps |
+---------+---------+----------+---------+
Examples:
trdsql -id " " -ih "SELECT \`PID\`, \`TTY\`, \`TIME\`, \`CMD\` FROM -"
trdsql -id " " -ih "SELECT \`PID\`, \`TTY\`, \`TIME\`, \`CMD\` FROM - WHERE \`PID\` = '3168'"
trdsql -id " " -ih "SELECT \`PID\`, count(\`PID\`) FROM - GROUP BY \`PID\`"
trdsql -id " " -ih "SELECT \`PID\`, \`TTY\`, \`TIME\`, \`CMD\` FROM - ORDER BY \`PID\` LIMIT 10"